The Experts below are selected from a list of 49920 Experts worldwide ranked by ideXlab platform
R. N. Saxena - One of the best experts on this subject based on the ideXlab platform.
-
effects of an external magnetic field on the hyperfine parameters in re2o3 re gd er nanoparticles measured by perturbed Angular Correlation spectroscopy
AIP Advances, 2020Co-Authors: E L Correa, R. N. Saxena, B Boschsantos, G A Cabrerapasca, A W CarbonariAbstract:In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Perturbed Angular Correlation (PAC) spectroscopy, a local technique, plus external magnetic field, was used to elucidate local interactions and possible mapping of the different contribution in these compounds. NPs were synthesized by thermal decomposition and characterized by transmission electron microscopy and X-ray diffraction. PAC measurements were performed using 111In(111Cd) as probe nuclei, with and without the application of an external magnetic field (EMF) of 0.5 T in different temperatures (50 K, 100 K, 200 K, 300 K). Results show that the hyperfine magnetic field is almost zero when the probe is located at the symmetric site, and ∼4 T and ∼5 T for Gd2O3 and Er2O3, respectively, when the probe occupies the asymmetric field.In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Perturbed Angular Correlation (PAC) spectroscopy, a local technique, plus external magnetic field, was used to elucidate local interactions and possible mapping of the different contribution in these compounds. NPs were synthesized by thermal decomposition and characterized by transmission electron microscopy and X-ray diffraction. PAC measurements were performed using 111In(111Cd) as probe nuclei, with and without the application of an external magnetic field (EMF) of 0.5 T in different temperatures (50 K, 100 K, 200 K, 300 K). Results show that the hyperfine magnetic field is almost zero when the probe is located at the symmetric site, and ∼4 T and ∼5 T for Gd2O3 and Er2O3, respectively, when the probe occupies the asymmetric field.
-
magnetic hyperfine field in antiferromagnetic rga2 r ce pr nd sm gd tb dy ho er studied by perturbed Angular Correlation spectroscopy using cd111
Journal of Applied Physics, 2013Co-Authors: F. H. M. Cavalcante, R. N. Saxena, H. Saitovitch, A W Carbonari, L F D Pereira, J T Cavalcante, M ForkerAbstract:The magnetic and electric hyperfine interactions of the nuclear probe Cd111 in the hexagonal antiferromagnetic rare earth-gallium RGa2 (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er) intermetallic compounds have been investigated by perturbed Angular Correlation (PAC) spectroscopy as a function of temperature. With the exception of R = Nd and Ho, the magnetic hyperfine field Bhf is roughly proportional to the spin projection (g − 1)J of the R constituent. However, in the group of the light rare earths, the variation of Bhf with (g − 1)J is much weaker than that for the heavy R constituents, in contrast to the trend reported for all rare earth intermetallics investigated up to now as well as to the trend of the magnetic ordering temperatures of RGa2. The orientation of the 4f spins relative to the c axis of RGa2 deduced from the angle between Bhf and the symmetry axis of the electric field gradient was found to be temperature independent and in agreement with the results of previous magnetization measurements...
-
investigation of the magnetic hyperfine field at r and zn sites in rzn r gd tb dy compounds using perturbed gamma gamma Angular Correlation spectroscopy with 140ce and 111cd as probe nuclei
Journal of Applied Physics, 2013Co-Authors: B Boschsantos, A W Carbonari, G A Cabrerapasca, M S Costa, R. N. SaxenaAbstract:The magnetic hyperfine field (Bhf) in RZn compounds (R = Gd, Tb, Dy) has been investigated by perturbed Angular Correlation spectroscopy using 140Ce and 111Cd as probe nuclei, respectively, at R and Zn sites, in order to study the origin of the magnetic coupling in these compounds. The results for 111Cd probe showed that the temperature dependence of Bhf roughly follows the Brillouin function for the R total Angular momentum J of each compound. The temperature dependence of Bhf measured with 140Ce probes showed, however, a sharp deviation from the Brillouin curve for all compounds, which was ascribed to the contribution of the 4f-electron of Ce3+ to Bhf.
-
effect of ge substitution for si on the magnetic hyperfine field in lamn2si2 compound measured by perturbed Angular Correlation spectroscopy with 140ce as probe nuclei
Journal of Applied Physics, 2013Co-Authors: B Boschsantos, A W Carbonari, G A Cabrerapasca, M S Costa, R. N. SaxenaAbstract:The effect of substitution of Ge for Si in LaMn2Si2 compound on the magnetic hyperfine field (Bhf) has been investigated by perturbed γ−γ Angular Correlation (PAC) spectroscopy using 140La(140Ce) as probe nuclei. This compound exhibits antiferromagnetism followed by a ferromagnetic ordering when temperature decreases. The behavior of the ferromagnetic transition when Ge gradually replaces Si, with concentrations of 20%, 40%, 80%, and 100% is discussed. PAC measurements were carried out in the temperature range from 15 K to 325 K. Results for LaMn2Si2 compound showed that the dependence of Bhf with temperature follows the expected behavior for the host magnetization and could be fitted by a Brillouin function for JMn = 5/2. However, the temperature dependence of Bhf for compounds when Si is gradually replaced by Ge showed a deviation from such a behavior, which gradually increases up to a strong deviation observed for LaMn2Ge2. This striking behavior was ascribed to the hybridization of d band of the host and f band of the Ce impurities, which is stronger when the unit cell volume increase as Si ions are substituted by Ge atoms.The effect of substitution of Ge for Si in LaMn2Si2 compound on the magnetic hyperfine field (Bhf) has been investigated by perturbed γ−γ Angular Correlation (PAC) spectroscopy using 140La(140Ce) as probe nuclei. This compound exhibits antiferromagnetism followed by a ferromagnetic ordering when temperature decreases. The behavior of the ferromagnetic transition when Ge gradually replaces Si, with concentrations of 20%, 40%, 80%, and 100% is discussed. PAC measurements were carried out in the temperature range from 15 K to 325 K. Results for LaMn2Si2 compound showed that the dependence of Bhf with temperature follows the expected behavior for the host magnetization and could be fitted by a Brillouin function for JMn = 5/2. However, the temperature dependence of Bhf for compounds when Si is gradually replaced by Ge showed a deviation from such a behavior, which gradually increases up to a strong deviation observed for LaMn2Ge2. This striking behavior was ascribed to the hybridization of d band of the host ...
-
magnetic hyperfine field at highly diluted ce impurities in the antiferromagnetic compound gdrh2si2 studied by perturbed gamma gamma Angular Correlation spectroscopy
Journal of Alloys and Compounds, 2012Co-Authors: G A Cabrerapasca, R. N. Saxena, A W Carbonari, B Boschsantos, J A H Coaquira, J A FilhoAbstract:Abstract The magnetic properties of GdRh2Si2 compound were investigated by hyperfine interactions and magnetization measurements. The temperature dependence of the magnetic hyperfine field (mhf) at highly diluted 140La–140Ce probe nuclei in the GdRh2Si2 compound was measured using perturbed gamma–gamma Angular Correlation spectroscopy. A well-defined magnetic interaction is observed at 140Ce substituting Gd atoms in the compound below the Neel temperature (TN). However, the temperature dependence of mhf shows a deviation from the expected Brillouin-like behavior and a sharp increase of mhf values is observed for temperatures below approximately half of TN. This behavior has been associated with an additional magnetic interaction which is ascribed to the polarization of Ce spin moment induced by the magnetic field coming from Gd ions. A model based on the molecular-field theory is used to fit the temperature dependence of the mhf. The mhf contributions from the probe atom itself and from the magnetic Gd ions of the host matrix are determined. The results are compared to previous measurements of mhf at 140Ce in Gd and GdAg compound. The contribution from the host to the mhf is discussed in terms of the f–s and f–d interactions.
A W Carbonari - One of the best experts on this subject based on the ideXlab platform.
-
effects of an external magnetic field on the hyperfine parameters in re2o3 re gd er nanoparticles measured by perturbed Angular Correlation spectroscopy
AIP Advances, 2020Co-Authors: E L Correa, R. N. Saxena, B Boschsantos, G A Cabrerapasca, A W CarbonariAbstract:In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Perturbed Angular Correlation (PAC) spectroscopy, a local technique, plus external magnetic field, was used to elucidate local interactions and possible mapping of the different contribution in these compounds. NPs were synthesized by thermal decomposition and characterized by transmission electron microscopy and X-ray diffraction. PAC measurements were performed using 111In(111Cd) as probe nuclei, with and without the application of an external magnetic field (EMF) of 0.5 T in different temperatures (50 K, 100 K, 200 K, 300 K). Results show that the hyperfine magnetic field is almost zero when the probe is located at the symmetric site, and ∼4 T and ∼5 T for Gd2O3 and Er2O3, respectively, when the probe occupies the asymmetric field.In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Perturbed Angular Correlation (PAC) spectroscopy, a local technique, plus external magnetic field, was used to elucidate local interactions and possible mapping of the different contribution in these compounds. NPs were synthesized by thermal decomposition and characterized by transmission electron microscopy and X-ray diffraction. PAC measurements were performed using 111In(111Cd) as probe nuclei, with and without the application of an external magnetic field (EMF) of 0.5 T in different temperatures (50 K, 100 K, 200 K, 300 K). Results show that the hyperfine magnetic field is almost zero when the probe is located at the symmetric site, and ∼4 T and ∼5 T for Gd2O3 and Er2O3, respectively, when the probe occupies the asymmetric field.
-
magnetic hyperfine field in antiferromagnetic rga2 r ce pr nd sm gd tb dy ho er studied by perturbed Angular Correlation spectroscopy using cd111
Journal of Applied Physics, 2013Co-Authors: F. H. M. Cavalcante, R. N. Saxena, H. Saitovitch, A W Carbonari, L F D Pereira, J T Cavalcante, M ForkerAbstract:The magnetic and electric hyperfine interactions of the nuclear probe Cd111 in the hexagonal antiferromagnetic rare earth-gallium RGa2 (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er) intermetallic compounds have been investigated by perturbed Angular Correlation (PAC) spectroscopy as a function of temperature. With the exception of R = Nd and Ho, the magnetic hyperfine field Bhf is roughly proportional to the spin projection (g − 1)J of the R constituent. However, in the group of the light rare earths, the variation of Bhf with (g − 1)J is much weaker than that for the heavy R constituents, in contrast to the trend reported for all rare earth intermetallics investigated up to now as well as to the trend of the magnetic ordering temperatures of RGa2. The orientation of the 4f spins relative to the c axis of RGa2 deduced from the angle between Bhf and the symmetry axis of the electric field gradient was found to be temperature independent and in agreement with the results of previous magnetization measurements...
-
investigation of the magnetic hyperfine field at r and zn sites in rzn r gd tb dy compounds using perturbed gamma gamma Angular Correlation spectroscopy with 140ce and 111cd as probe nuclei
Journal of Applied Physics, 2013Co-Authors: B Boschsantos, A W Carbonari, G A Cabrerapasca, M S Costa, R. N. SaxenaAbstract:The magnetic hyperfine field (Bhf) in RZn compounds (R = Gd, Tb, Dy) has been investigated by perturbed Angular Correlation spectroscopy using 140Ce and 111Cd as probe nuclei, respectively, at R and Zn sites, in order to study the origin of the magnetic coupling in these compounds. The results for 111Cd probe showed that the temperature dependence of Bhf roughly follows the Brillouin function for the R total Angular momentum J of each compound. The temperature dependence of Bhf measured with 140Ce probes showed, however, a sharp deviation from the Brillouin curve for all compounds, which was ascribed to the contribution of the 4f-electron of Ce3+ to Bhf.
-
effect of ge substitution for si on the magnetic hyperfine field in lamn2si2 compound measured by perturbed Angular Correlation spectroscopy with 140ce as probe nuclei
Journal of Applied Physics, 2013Co-Authors: B Boschsantos, A W Carbonari, G A Cabrerapasca, M S Costa, R. N. SaxenaAbstract:The effect of substitution of Ge for Si in LaMn2Si2 compound on the magnetic hyperfine field (Bhf) has been investigated by perturbed γ−γ Angular Correlation (PAC) spectroscopy using 140La(140Ce) as probe nuclei. This compound exhibits antiferromagnetism followed by a ferromagnetic ordering when temperature decreases. The behavior of the ferromagnetic transition when Ge gradually replaces Si, with concentrations of 20%, 40%, 80%, and 100% is discussed. PAC measurements were carried out in the temperature range from 15 K to 325 K. Results for LaMn2Si2 compound showed that the dependence of Bhf with temperature follows the expected behavior for the host magnetization and could be fitted by a Brillouin function for JMn = 5/2. However, the temperature dependence of Bhf for compounds when Si is gradually replaced by Ge showed a deviation from such a behavior, which gradually increases up to a strong deviation observed for LaMn2Ge2. This striking behavior was ascribed to the hybridization of d band of the host and f band of the Ce impurities, which is stronger when the unit cell volume increase as Si ions are substituted by Ge atoms.The effect of substitution of Ge for Si in LaMn2Si2 compound on the magnetic hyperfine field (Bhf) has been investigated by perturbed γ−γ Angular Correlation (PAC) spectroscopy using 140La(140Ce) as probe nuclei. This compound exhibits antiferromagnetism followed by a ferromagnetic ordering when temperature decreases. The behavior of the ferromagnetic transition when Ge gradually replaces Si, with concentrations of 20%, 40%, 80%, and 100% is discussed. PAC measurements were carried out in the temperature range from 15 K to 325 K. Results for LaMn2Si2 compound showed that the dependence of Bhf with temperature follows the expected behavior for the host magnetization and could be fitted by a Brillouin function for JMn = 5/2. However, the temperature dependence of Bhf for compounds when Si is gradually replaced by Ge showed a deviation from such a behavior, which gradually increases up to a strong deviation observed for LaMn2Ge2. This striking behavior was ascribed to the hybridization of d band of the host ...
-
magnetic hyperfine field at highly diluted ce impurities in the antiferromagnetic compound gdrh2si2 studied by perturbed gamma gamma Angular Correlation spectroscopy
Journal of Alloys and Compounds, 2012Co-Authors: G A Cabrerapasca, R. N. Saxena, A W Carbonari, B Boschsantos, J A H Coaquira, J A FilhoAbstract:Abstract The magnetic properties of GdRh2Si2 compound were investigated by hyperfine interactions and magnetization measurements. The temperature dependence of the magnetic hyperfine field (mhf) at highly diluted 140La–140Ce probe nuclei in the GdRh2Si2 compound was measured using perturbed gamma–gamma Angular Correlation spectroscopy. A well-defined magnetic interaction is observed at 140Ce substituting Gd atoms in the compound below the Neel temperature (TN). However, the temperature dependence of mhf shows a deviation from the expected Brillouin-like behavior and a sharp increase of mhf values is observed for temperatures below approximately half of TN. This behavior has been associated with an additional magnetic interaction which is ascribed to the polarization of Ce spin moment induced by the magnetic field coming from Gd ions. A model based on the molecular-field theory is used to fit the temperature dependence of the mhf. The mhf contributions from the probe atom itself and from the magnetic Gd ions of the host matrix are determined. The results are compared to previous measurements of mhf at 140Ce in Gd and GdAg compound. The contribution from the host to the mhf is discussed in terms of the f–s and f–d interactions.
M Forker - One of the best experts on this subject based on the ideXlab platform.
-
magnetic hyperfine field in antiferromagnetic rga2 r ce pr nd sm gd tb dy ho er studied by perturbed Angular Correlation spectroscopy using cd111
Journal of Applied Physics, 2013Co-Authors: F. H. M. Cavalcante, R. N. Saxena, H. Saitovitch, A W Carbonari, L F D Pereira, J T Cavalcante, M ForkerAbstract:The magnetic and electric hyperfine interactions of the nuclear probe Cd111 in the hexagonal antiferromagnetic rare earth-gallium RGa2 (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er) intermetallic compounds have been investigated by perturbed Angular Correlation (PAC) spectroscopy as a function of temperature. With the exception of R = Nd and Ho, the magnetic hyperfine field Bhf is roughly proportional to the spin projection (g − 1)J of the R constituent. However, in the group of the light rare earths, the variation of Bhf with (g − 1)J is much weaker than that for the heavy R constituents, in contrast to the trend reported for all rare earth intermetallics investigated up to now as well as to the trend of the magnetic ordering temperatures of RGa2. The orientation of the 4f spins relative to the c axis of RGa2 deduced from the angle between Bhf and the symmetry axis of the electric field gradient was found to be temperature independent and in agreement with the results of previous magnetization measurements...
-
the magnetic hyperfine field of 111cd in the rare earth nickel laves phases rni2
Hyperfine Interactions, 2004Co-Authors: Stefan Muller, P De La Presa, M ForkerAbstract:The magnetic hyperfine field of 111Cd in the C15 Laves phases RNi2 has been investigated by perturbed Angular Correlation (PAC) spectroscopy as a function of temperature for the rare earth constituents R = Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm.
-
vacancy motion in rare earth deficient r 1 x ni 2 laves phases observed by perturbed Angular Correlation spectroscopy
Physical Review B, 2004Co-Authors: M Forker, P De La Presa, Stefan Muller, A Lindbaum, E GratzAbstract:Rare-earth-deficient R_(1-x)Ni_2 Laves phases, which reportedly crystallize in a C15 superstructure with ordered R vacancies, have been investigated by perturbed Angular Correlation (PAC) measurements of electric quadrupole interactions at the site of the probe nucleus ^111Cd. Although ^111Cd resides on the cubic R site, a strong axially symmetric quadrupole interaction (QI) with frequencies ν(q)approximate to265-275 MHz has been found in the paramagnetic phases of R_(1-x)Ni_2 with R=Pr,Nd,Sm,Gd. This interaction is not observed for the heavy R constituents R=Tb,Dy,Ho,Er. The fraction of probe nuclei subject to the QI in R_(1-x)Ni_2, R=Pr,Nd,Sm,Gd, decreases from 100% at low temperatures to zero at T>300 K and 500 K for R=Sm,Gd and R=Pr,Nd, respectively. At T=100 K the QI is static within the PAC time window, but at T=200 K fluctuations with Correlation times τ_(C) 500 K nuclear spin relaxation related to vacancy hopping is observed in nearly all R_(1-x)N_i2. Auxiliary ^111Cd PAC measurements have been carried in Sc_0.95Ni_2, ScNi_2, ScNi_0.97, Gd_2Ni_(17), GdNi_5, GdNi_3, and GdNi.
-
perturbed Angular Correlation study of the magnetic phase transitions in the rare earth cobalt laves phases rco2
Physical Review B, 2003Co-Authors: M Forker, P De La Presa, Stefan Muller, A F PasquevichAbstract:The order and other properties of the magnetic phase transitions in the rare-earth ( R)-cobalt Laves phases RCo2 have been studied for R5Gd, Tb, Dy, Ho, Er, Sm, Nd, and Pr by measuring the temperature dependence of the magnetic hyperfine interaction of the nuclear probe 111 Cd on the cubic R sites using the perturbed Angular Correlation technique. Both for heavy and light R constituents the transitions change from second order ~Gd, Tb, Sm! to first order ~Dy, Ho, Er, Nd, Pr! at order temperatures of 150‐200 K. For heavy R constituents, the order deduced from the hyperfine interaction is in agreement with previous investigations. The observation of first order transitions in NdCo2 and PrCo2, however, is unexpected. In earlier studies the transitions in these compounds are usually classified as second order transitions. Both in the heavy and the light RCo2 the discontinuous jump of the hyperfine interaction at the first order transitions increases with decreasing order temperature. This trend implies that the Co magnetization at the transition increases with decreasing TC which can be related to the temperature dependence of the coefficient of the M 4 term of the free energy in the Wohlfarth-Rhodes-Shimizu theory of itinerant electron magnetism. All compounds investigated presented a spread of the order temperature of ;1 ‐2 K which results in a coexistence of the paramagnetic and the magnetically ordered phase near the transition and causes a critical increase of the relative linewidth of the
B Boschsantos - One of the best experts on this subject based on the ideXlab platform.
-
effects of an external magnetic field on the hyperfine parameters in re2o3 re gd er nanoparticles measured by perturbed Angular Correlation spectroscopy
AIP Advances, 2020Co-Authors: E L Correa, R. N. Saxena, B Boschsantos, G A Cabrerapasca, A W CarbonariAbstract:In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Perturbed Angular Correlation (PAC) spectroscopy, a local technique, plus external magnetic field, was used to elucidate local interactions and possible mapping of the different contribution in these compounds. NPs were synthesized by thermal decomposition and characterized by transmission electron microscopy and X-ray diffraction. PAC measurements were performed using 111In(111Cd) as probe nuclei, with and without the application of an external magnetic field (EMF) of 0.5 T in different temperatures (50 K, 100 K, 200 K, 300 K). Results show that the hyperfine magnetic field is almost zero when the probe is located at the symmetric site, and ∼4 T and ∼5 T for Gd2O3 and Er2O3, respectively, when the probe occupies the asymmetric field.In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Perturbed Angular Correlation (PAC) spectroscopy, a local technique, plus external magnetic field, was used to elucidate local interactions and possible mapping of the different contribution in these compounds. NPs were synthesized by thermal decomposition and characterized by transmission electron microscopy and X-ray diffraction. PAC measurements were performed using 111In(111Cd) as probe nuclei, with and without the application of an external magnetic field (EMF) of 0.5 T in different temperatures (50 K, 100 K, 200 K, 300 K). Results show that the hyperfine magnetic field is almost zero when the probe is located at the symmetric site, and ∼4 T and ∼5 T for Gd2O3 and Er2O3, respectively, when the probe occupies the asymmetric field.
-
investigation of the magnetic hyperfine field at r and zn sites in rzn r gd tb dy compounds using perturbed gamma gamma Angular Correlation spectroscopy with 140ce and 111cd as probe nuclei
Journal of Applied Physics, 2013Co-Authors: B Boschsantos, A W Carbonari, G A Cabrerapasca, M S Costa, R. N. SaxenaAbstract:The magnetic hyperfine field (Bhf) in RZn compounds (R = Gd, Tb, Dy) has been investigated by perturbed Angular Correlation spectroscopy using 140Ce and 111Cd as probe nuclei, respectively, at R and Zn sites, in order to study the origin of the magnetic coupling in these compounds. The results for 111Cd probe showed that the temperature dependence of Bhf roughly follows the Brillouin function for the R total Angular momentum J of each compound. The temperature dependence of Bhf measured with 140Ce probes showed, however, a sharp deviation from the Brillouin curve for all compounds, which was ascribed to the contribution of the 4f-electron of Ce3+ to Bhf.
-
effect of ge substitution for si on the magnetic hyperfine field in lamn2si2 compound measured by perturbed Angular Correlation spectroscopy with 140ce as probe nuclei
Journal of Applied Physics, 2013Co-Authors: B Boschsantos, A W Carbonari, G A Cabrerapasca, M S Costa, R. N. SaxenaAbstract:The effect of substitution of Ge for Si in LaMn2Si2 compound on the magnetic hyperfine field (Bhf) has been investigated by perturbed γ−γ Angular Correlation (PAC) spectroscopy using 140La(140Ce) as probe nuclei. This compound exhibits antiferromagnetism followed by a ferromagnetic ordering when temperature decreases. The behavior of the ferromagnetic transition when Ge gradually replaces Si, with concentrations of 20%, 40%, 80%, and 100% is discussed. PAC measurements were carried out in the temperature range from 15 K to 325 K. Results for LaMn2Si2 compound showed that the dependence of Bhf with temperature follows the expected behavior for the host magnetization and could be fitted by a Brillouin function for JMn = 5/2. However, the temperature dependence of Bhf for compounds when Si is gradually replaced by Ge showed a deviation from such a behavior, which gradually increases up to a strong deviation observed for LaMn2Ge2. This striking behavior was ascribed to the hybridization of d band of the host and f band of the Ce impurities, which is stronger when the unit cell volume increase as Si ions are substituted by Ge atoms.The effect of substitution of Ge for Si in LaMn2Si2 compound on the magnetic hyperfine field (Bhf) has been investigated by perturbed γ−γ Angular Correlation (PAC) spectroscopy using 140La(140Ce) as probe nuclei. This compound exhibits antiferromagnetism followed by a ferromagnetic ordering when temperature decreases. The behavior of the ferromagnetic transition when Ge gradually replaces Si, with concentrations of 20%, 40%, 80%, and 100% is discussed. PAC measurements were carried out in the temperature range from 15 K to 325 K. Results for LaMn2Si2 compound showed that the dependence of Bhf with temperature follows the expected behavior for the host magnetization and could be fitted by a Brillouin function for JMn = 5/2. However, the temperature dependence of Bhf for compounds when Si is gradually replaced by Ge showed a deviation from such a behavior, which gradually increases up to a strong deviation observed for LaMn2Ge2. This striking behavior was ascribed to the hybridization of d band of the host ...
-
magnetic hyperfine field at highly diluted ce impurities in the antiferromagnetic compound gdrh2si2 studied by perturbed gamma gamma Angular Correlation spectroscopy
Journal of Alloys and Compounds, 2012Co-Authors: G A Cabrerapasca, R. N. Saxena, A W Carbonari, B Boschsantos, J A H Coaquira, J A FilhoAbstract:Abstract The magnetic properties of GdRh2Si2 compound were investigated by hyperfine interactions and magnetization measurements. The temperature dependence of the magnetic hyperfine field (mhf) at highly diluted 140La–140Ce probe nuclei in the GdRh2Si2 compound was measured using perturbed gamma–gamma Angular Correlation spectroscopy. A well-defined magnetic interaction is observed at 140Ce substituting Gd atoms in the compound below the Neel temperature (TN). However, the temperature dependence of mhf shows a deviation from the expected Brillouin-like behavior and a sharp increase of mhf values is observed for temperatures below approximately half of TN. This behavior has been associated with an additional magnetic interaction which is ascribed to the polarization of Ce spin moment induced by the magnetic field coming from Gd ions. A model based on the molecular-field theory is used to fit the temperature dependence of the mhf. The mhf contributions from the probe atom itself and from the magnetic Gd ions of the host matrix are determined. The results are compared to previous measurements of mhf at 140Ce in Gd and GdAg compound. The contribution from the host to the mhf is discussed in terms of the f–s and f–d interactions.
G A Cabrerapasca - One of the best experts on this subject based on the ideXlab platform.
-
effects of an external magnetic field on the hyperfine parameters in re2o3 re gd er nanoparticles measured by perturbed Angular Correlation spectroscopy
AIP Advances, 2020Co-Authors: E L Correa, R. N. Saxena, B Boschsantos, G A Cabrerapasca, A W CarbonariAbstract:In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Perturbed Angular Correlation (PAC) spectroscopy, a local technique, plus external magnetic field, was used to elucidate local interactions and possible mapping of the different contribution in these compounds. NPs were synthesized by thermal decomposition and characterized by transmission electron microscopy and X-ray diffraction. PAC measurements were performed using 111In(111Cd) as probe nuclei, with and without the application of an external magnetic field (EMF) of 0.5 T in different temperatures (50 K, 100 K, 200 K, 300 K). Results show that the hyperfine magnetic field is almost zero when the probe is located at the symmetric site, and ∼4 T and ∼5 T for Gd2O3 and Er2O3, respectively, when the probe occupies the asymmetric field.In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Perturbed Angular Correlation (PAC) spectroscopy, a local technique, plus external magnetic field, was used to elucidate local interactions and possible mapping of the different contribution in these compounds. NPs were synthesized by thermal decomposition and characterized by transmission electron microscopy and X-ray diffraction. PAC measurements were performed using 111In(111Cd) as probe nuclei, with and without the application of an external magnetic field (EMF) of 0.5 T in different temperatures (50 K, 100 K, 200 K, 300 K). Results show that the hyperfine magnetic field is almost zero when the probe is located at the symmetric site, and ∼4 T and ∼5 T for Gd2O3 and Er2O3, respectively, when the probe occupies the asymmetric field.
-
investigation of the magnetic hyperfine field at r and zn sites in rzn r gd tb dy compounds using perturbed gamma gamma Angular Correlation spectroscopy with 140ce and 111cd as probe nuclei
Journal of Applied Physics, 2013Co-Authors: B Boschsantos, A W Carbonari, G A Cabrerapasca, M S Costa, R. N. SaxenaAbstract:The magnetic hyperfine field (Bhf) in RZn compounds (R = Gd, Tb, Dy) has been investigated by perturbed Angular Correlation spectroscopy using 140Ce and 111Cd as probe nuclei, respectively, at R and Zn sites, in order to study the origin of the magnetic coupling in these compounds. The results for 111Cd probe showed that the temperature dependence of Bhf roughly follows the Brillouin function for the R total Angular momentum J of each compound. The temperature dependence of Bhf measured with 140Ce probes showed, however, a sharp deviation from the Brillouin curve for all compounds, which was ascribed to the contribution of the 4f-electron of Ce3+ to Bhf.
-
effect of ge substitution for si on the magnetic hyperfine field in lamn2si2 compound measured by perturbed Angular Correlation spectroscopy with 140ce as probe nuclei
Journal of Applied Physics, 2013Co-Authors: B Boschsantos, A W Carbonari, G A Cabrerapasca, M S Costa, R. N. SaxenaAbstract:The effect of substitution of Ge for Si in LaMn2Si2 compound on the magnetic hyperfine field (Bhf) has been investigated by perturbed γ−γ Angular Correlation (PAC) spectroscopy using 140La(140Ce) as probe nuclei. This compound exhibits antiferromagnetism followed by a ferromagnetic ordering when temperature decreases. The behavior of the ferromagnetic transition when Ge gradually replaces Si, with concentrations of 20%, 40%, 80%, and 100% is discussed. PAC measurements were carried out in the temperature range from 15 K to 325 K. Results for LaMn2Si2 compound showed that the dependence of Bhf with temperature follows the expected behavior for the host magnetization and could be fitted by a Brillouin function for JMn = 5/2. However, the temperature dependence of Bhf for compounds when Si is gradually replaced by Ge showed a deviation from such a behavior, which gradually increases up to a strong deviation observed for LaMn2Ge2. This striking behavior was ascribed to the hybridization of d band of the host and f band of the Ce impurities, which is stronger when the unit cell volume increase as Si ions are substituted by Ge atoms.The effect of substitution of Ge for Si in LaMn2Si2 compound on the magnetic hyperfine field (Bhf) has been investigated by perturbed γ−γ Angular Correlation (PAC) spectroscopy using 140La(140Ce) as probe nuclei. This compound exhibits antiferromagnetism followed by a ferromagnetic ordering when temperature decreases. The behavior of the ferromagnetic transition when Ge gradually replaces Si, with concentrations of 20%, 40%, 80%, and 100% is discussed. PAC measurements were carried out in the temperature range from 15 K to 325 K. Results for LaMn2Si2 compound showed that the dependence of Bhf with temperature follows the expected behavior for the host magnetization and could be fitted by a Brillouin function for JMn = 5/2. However, the temperature dependence of Bhf for compounds when Si is gradually replaced by Ge showed a deviation from such a behavior, which gradually increases up to a strong deviation observed for LaMn2Ge2. This striking behavior was ascribed to the hybridization of d band of the host ...
-
magnetic hyperfine field at highly diluted ce impurities in the antiferromagnetic compound gdrh2si2 studied by perturbed gamma gamma Angular Correlation spectroscopy
Journal of Alloys and Compounds, 2012Co-Authors: G A Cabrerapasca, R. N. Saxena, A W Carbonari, B Boschsantos, J A H Coaquira, J A FilhoAbstract:Abstract The magnetic properties of GdRh2Si2 compound were investigated by hyperfine interactions and magnetization measurements. The temperature dependence of the magnetic hyperfine field (mhf) at highly diluted 140La–140Ce probe nuclei in the GdRh2Si2 compound was measured using perturbed gamma–gamma Angular Correlation spectroscopy. A well-defined magnetic interaction is observed at 140Ce substituting Gd atoms in the compound below the Neel temperature (TN). However, the temperature dependence of mhf shows a deviation from the expected Brillouin-like behavior and a sharp increase of mhf values is observed for temperatures below approximately half of TN. This behavior has been associated with an additional magnetic interaction which is ascribed to the polarization of Ce spin moment induced by the magnetic field coming from Gd ions. A model based on the molecular-field theory is used to fit the temperature dependence of the mhf. The mhf contributions from the probe atom itself and from the magnetic Gd ions of the host matrix are determined. The results are compared to previous measurements of mhf at 140Ce in Gd and GdAg compound. The contribution from the host to the mhf is discussed in terms of the f–s and f–d interactions.