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Jonas Fransson - One of the best experts on this subject based on the ideXlab platform.
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Spin Inelastic Electron Tunneling Spectroscopy on Local Magnetic Moment Embedded in Josephson Junction
EPL (Europhysics Letters), 2014Co-Authors: Peter Berggren, Jonas FranssonAbstract:Recent experimental conductance measurements performed on paraMagnetic molecular adsorbates on a superconducting surface, using superconducting scanning tunneling microscopy techniques, are theoretically investigated. For low temperatures, we demonstrate that tunneling current assisted excitations of the Local Magnetic Moment cannot occur for voltage biases smaller than the superconducting gap of the scanning tunneling microscope. The Magnetic Moment is only excited for voltages corresponding to the sum of the superconducting gap and the spin excitation energies. In excellent agreement with experiment, we show that pumping into higher excitations give additional current signatures by accumulation of density in the lower ones. Using external Magnetic fields, we Zeeman split possible degeneracy and thereby resolve all excitations comprised in the Magnetic Moment.
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spin inelastic electron tunneling spectroscopy on Local Magnetic Moment embedded in josephson junction
EPL, 2014Co-Authors: Peter Berggren, Jonas FranssonAbstract:Recent experimental conductance measurements performed on paraMagnetic molecular adsorbates on a superconducting surface, using superconducting scanning tunneling microscopy techniques, are theoretically investigated. For low temperatures, we demonstrate that tunneling current assisted excitations of the Local Magnetic Moment cannot occur for voltage biases smaller than the superconducting gap of the scanning tunneling microscope. The Magnetic Moment is only excited for voltages corresponding to the sum of the superconducting gap and the spin excitation energies. In excellent agreement with experiment, we show that pumping into higher excitations gives additional current signatures by accumulation of density in the lower ones. Using external Magnetic fields, we Zeeman-split the possible degeneracy and thereby resolve all excitations comprised in the Magnetic Moment.
A. Troper - One of the best experts on this subject based on the ideXlab platform.
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On the Local Magnetic Moment formation and on the Magnetic hyperfine field at isoelectronic noble impurities (Cu, Ag, Au) diluted in GdZn: Period effect
Journal of Magnetism and Magnetic Materials, 2017Co-Authors: A.l. De Oliveira, N.a. De Oliveira, C. M. Chaves, A. TroperAbstract:Abstract In this work we study the period effect on the Local Magnetic Moment and the related Magnetic hyperfine field at non-Magnetic s-p impurities (Cu, Ag, Au) diluted in GdZn, the impurity occupying a Zn site. The period effect refers to the difference of the Local Moment and the hyperfine fields in these noble isoelectronic ( nd 10 ms 1 , n=3, 4, 5, m=4, 5, 6) impurities that apparently would have similar Moments and hyperfine fields, which is not the case. We show that the difference on the Local Moments is due to the differences of volumes of the impurities with respect to the host Zn ion while the difference of the hyperfine fields is due to different contact parameter A ( Z imp ) , which depend mainly on the principal quantum numbers of the impurity shell m. We further extend our model to calculate the temperature variation of the Local Magnetic Moment and of the hyperfine field for each impurity; for this calculation we adopt a functional integral approach in the static approximation.
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Local Magnetic Moment formation and Magnetic hyperfine fields at cd impurity in ral2 r rare earth metal
AIP Advances, 2012Co-Authors: A.l. De Oliveira, N.a. De Oliveira, C. M. Chaves, A. TroperAbstract:A model to calculate self-consistently the Local Magnetic Moment and the Magnetic hyperfine field Bhf at the nuclei of 119Cd in RAl2 (R = rare earth metal), where the impurity occupies the Al site, is proposed. The Local Magnetic Moment and the Magnetic hyperfine field Bhf have two contributions each: one arising from the 4f electrons of the R ions and the other arising from the 3p electrons of Al. Our results are in good agreement with the experimental data.
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Local Magnetic Moment formation and Magnetic hyperfine fields at Cd impurity in RAl2 (R = rare earth metal)
AIP Advances, 2012Co-Authors: A.l. De Oliveira, N.a. De Oliveira, C. M. Chaves, A. TroperAbstract:A model to calculate self-consistently the Local Magnetic Moment and the Magnetic hyperfine field Bhf at the nuclei of 119Cd in RAl2 (R = rare earth metal), where the impurity occupies the Al site, is proposed. The Local Magnetic Moment and the Magnetic hyperfine field Bhf have two contributions each: one arising from the 4f electrons of the R ions and the other arising from the 3p electrons of Al. Our results are in good agreement with the experimental data.
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Local Magnetic Moment formation at 119Sn Mössbauer impurity in RFe2 (R=rare-earth metals) Laves phases compounds
Journal of Magnetism and Magnetic Materials, 2010Co-Authors: A.l. De Oliveira, N.a. De Oliveira, A. TroperAbstract:Abstract The purpose of the present work is to theoretically study the Local Magnetic Moment formation and the systematics of the Magnetic hyperfine fields at a non-Magnetic s–p Mossbauer 119Sn impurity diluted on R sites ( R = rare-earth metals ) of the cubic Laves phases intermetallic compounds R Fe 2 . One considers that the Magnetic hyperfine field has two contributions (i) the contribution from R ions, calculated via an extended Daniel–Friedel [J. Phys. Chem. Solids 24 (1963) 1601] model and (ii) the contribution from the induced Magnetic Moments arising from the Fe neighboring sites. We have in this case a two-center Blandin–Campbell-like [Phys. Rev. Lett. 31 (1973) 51; J. Magn. Magn. Mater. 1 (1975) 1] problem, where a Magnetic 3d-element located at a distance from the 119Sn impurity gives an extra magnetization to a polarized electron gas which is strongly charge perturbed at the 119Sn impurity site. We also include in the model, the nearest-neighbor perturbation due to the translational invariance breaking introduced by the impurity. Our self-consistent total Magnetic hyperfine field calculations are in a very good agreement with recent experimental data.
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Local Magnetic Moment formation at Sn119 Mössbauer impurity in RCo2 (R=Gd,Tb,Dy,Ho,Er) Laves phase compounds
Journal of Applied Physics, 2008Co-Authors: A.l. De Oliveira, N.a. De Oliveira, A. TroperAbstract:In this work, we theoretically study the Local Magnetic Moment formation and the systematics of the Magnetic hyperfine fields at a Mosbauer Sn119 impurity diluted at the R site (R=Gd,Tb,Dy,Ho,Er) of the cubic Laves phase intermetallic compounds RCo2. One considers that the Magnetic hyperfine fields have two contributions, (i) the contribution from R ions, calculated via an extended Daniel-Friedel [J. Phys. Chem. Solids 24, 1601 (1963)] model, and (ii) the contribution from the induced Magnetic Moments arising from the Co neighboring sites. Our calculated self-consistent total Magnetic hyperfine fields are in a good agreement with recent experimental data.
Peter Berggren - One of the best experts on this subject based on the ideXlab platform.
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Spin Inelastic Electron Tunneling Spectroscopy on Local Magnetic Moment Embedded in Josephson Junction
EPL (Europhysics Letters), 2014Co-Authors: Peter Berggren, Jonas FranssonAbstract:Recent experimental conductance measurements performed on paraMagnetic molecular adsorbates on a superconducting surface, using superconducting scanning tunneling microscopy techniques, are theoretically investigated. For low temperatures, we demonstrate that tunneling current assisted excitations of the Local Magnetic Moment cannot occur for voltage biases smaller than the superconducting gap of the scanning tunneling microscope. The Magnetic Moment is only excited for voltages corresponding to the sum of the superconducting gap and the spin excitation energies. In excellent agreement with experiment, we show that pumping into higher excitations give additional current signatures by accumulation of density in the lower ones. Using external Magnetic fields, we Zeeman split possible degeneracy and thereby resolve all excitations comprised in the Magnetic Moment.
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spin inelastic electron tunneling spectroscopy on Local Magnetic Moment embedded in josephson junction
EPL, 2014Co-Authors: Peter Berggren, Jonas FranssonAbstract:Recent experimental conductance measurements performed on paraMagnetic molecular adsorbates on a superconducting surface, using superconducting scanning tunneling microscopy techniques, are theoretically investigated. For low temperatures, we demonstrate that tunneling current assisted excitations of the Local Magnetic Moment cannot occur for voltage biases smaller than the superconducting gap of the scanning tunneling microscope. The Magnetic Moment is only excited for voltages corresponding to the sum of the superconducting gap and the spin excitation energies. In excellent agreement with experiment, we show that pumping into higher excitations gives additional current signatures by accumulation of density in the lower ones. Using external Magnetic fields, we Zeeman-split the possible degeneracy and thereby resolve all excitations comprised in the Magnetic Moment.
B.i. Reser - One of the best experts on this subject based on the ideXlab platform.
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Local Moments in the Dynamic Spin-Fluctuation Theory of Metallic Magnetism
Solid State Phenomena, 2012Co-Authors: Nikolai B. Melnikov, B.i. Reser, V. I. GrebennikovAbstract:In the dynamic spin-fluctuation theory extended by taking into account higher-order terms of the free energy and uniform fluctuations along with the Local ones, simple computational formulae for Local Magnetic Moment are obtained. The temperature dependence of Local Magnetic Moment in the Fe0.65Ni0.35 Invar is calculated. Good agreement with the experimentally estimated value of the Magnetic volume change is achieved.
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Magnetic properties of Fe–Ni invar calculated in the dynamic non-Local approximation of the spin fluctuation theory
Journal of Physics: Condensed Matter, 2004Co-Authors: B.i. ReserAbstract:The magnetization, the Curie temperature, the Local Magnetic Moment and susceptibilities of Fe–Ni invar are calculated, using the first-principles density of states and the dynamic non-Local approximation of the spin-fluctuation theory. A good agreement with experimental data over a wide range of temperatures, including low temperatures, has been found.
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Calculation of Local Magnetic characteristics of ferroMagnetic metals taking into account the dynamic spin fluctuations
Journal of Magnetism and Magnetic Materials, 2003Co-Authors: B.i. ReserAbstract:The numerical calculations of the transverse and longitudinal susceptibilities, the dynamic spin correlation function and the Local Magnetic Moment of ferroMagnetic metals are performed taking into account the real band structure and dynamic spin fluctuations. A good agreement between theory and experiments on magnetovolume effect and neutron scattering has been found.
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Numerical calculation of Local Magnetic characteristics of Fe, Co and Ni at finite temperatures
Journal of Physics: Condensed Matter, 2002Co-Authors: B.i. ReserAbstract:The transverse and longitudinal Local susceptibilities, the dynamic spin correlation function and the Local Magnetic Moment of Fe, Co and Ni are calculated, using the first-principles density of states and the dynamic non-Local approximation of the spin-fluctuation theory. A remarkable agreement between theory and experiments on magnetovolume effect and neutron scattering has been found.
V. P. Antropov - One of the best experts on this subject based on the ideXlab platform.
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Effects of spin fluctuations and anomalous thermal expansion of δ-Pu
Physical Review B, 2010Co-Authors: A. Solontsov, V. P. AntropovAbstract:We suggest a model for the Magnetic dynamics of - plutonium and its alloys in order to show that the dynamical fluctuations of the magnetization density, or spin fluctuations, may be responsible for the anomalies of their observed thermal expansion. We show that due to strong magneto-elastic coupling, spin fluctuations may essentially contribute to the volume strain by giving a negative magneto-volume contribution that is proportional to the squared Local Magnetic Moment and the Magnetic Gruneisen constant which is negative in - plutonium. In the presented model, the Local Magnetic Moment increases as the temperature rises, resulting in the interplay between the positive contributions to the volume strain from the lattice and the negative contribution from spin fluctuations, and finally leads to the Invar anomaly or to the negative coefficient of thermal expansion. Our results agree closely with the measured thermal expansion data for Pu-Ga alloys.