The Experts below are selected from a list of 6597 Experts worldwide ranked by ideXlab platform
Eiji Saitoh - One of the best experts on this subject based on the ideXlab platform.
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Spin colossal magnetoresistance in an antiferromagnetic insulator
Nature materials, 2018Co-Authors: Zhiyong Qiu, Dazhi Hou, Joseph Barker, Kei Yamamoto, Olena Gomonay, Eiji SaitohAbstract:Colossal magnetoresistance (CMR) refers to a large change in electrical conductivity induced by a magnetic field in the vicinity of a metal-insulator transition and has inspired extensive studies for decades\cite{Ramirez1997, Tokura2006}. Here we demonstrate an analogous spin effect near the Neel Temperature $T_{\rm{N}}$=296 K of the antiferromagnetic insulator \CrO. Using a yttrium iron garnet \YIG/\CrO/Pt trilayer, we injected a spin current from the YIG into the \CrO layer, and collected via the inverse spin Hall effect the signal transmitted in the heavy metal Pt. We observed a change by two orders of magnitude in the transmitted spin current within 14 K of the Neel Temperature. This transition between spin conducting and nonconducting states could be also modulated by a magnetic field in isothermal conditions. This effect, that we term spin colossal magnetoresistance (SCMR), has the potential to simplify the design of fundamental spintronics components, for instance enabling the realization of spin current switches or spin-current based memories.
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spin colossal magnetoresistance in an antiferromagnetic insulator
Nature Materials, 2018Co-Authors: Zhiyong Qiu, Dazhi Hou, Joseph Barker, Kei Yamamoto, Olena Gomonay, Eiji SaitohAbstract:Colossal magnetoresistance (CMR) refers to a large change in electrical conductivity induced by a magnetic field in the vicinity of a metal–insulator transition and has inspired extensive studies for decades1,2. Here we demonstrate an analogous spin effect near the Neel Temperature, TN = 296 K, of the antiferromagnetic insulator Cr2O3. Using a yttrium iron garnet YIG/Cr2O3/Pt trilayer, we injected a spin current from the YIG into the Cr2O3 layer and collected, via the inverse spin Hall effect, the spin signal transmitted into the heavy metal Pt. We observed a two orders of magnitude difference in the transmitted spin current within 14 K of the Neel Temperature. This transition between spin conducting and non-conducting states was also modulated by a magnetic field in isothermal conditions. This effect, which we term spin colossal magnetoresistance (SCMR), has the potential to simplify the design of fundamental spintronics components, for instance, by enabling the realization of spin-current switches or spin-current-based memories.
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electric Neel Temperature determination of an antiferromagnetic insulator film
IEEE International Magnetics Conference, 2015Co-Authors: Zhiyong Qiu, D Hou, Eiji SaitohAbstract:Antiferromagnetism, which manifests as the antiparallel alignment of neighboring magnetic moments, is one of the most important magnetic orderings. Although sharing nearly the same mechanism with ferromagnetism, antiferromagnetism was discovered much later due to the compensated magnetic structure which is of very weak response to magnetic field. Because of the same reason, the characterization of the ordering Temperature and magnetic structure of antiferromagnetic material is much more difficult than that of the ferromagnet, which usually requires higher sensitivity in magnetometry and larger sample volume. When the antiferromagnetic material is made into a geometry with confinement such as ultra-thin film, these measurements are especially challenging. In spite of these difficulties, the research interests of antiferromagetism in thin films have been growing in the last several decades with the motivations not only from commercial applications like exchange bias, but also form the emergence of novel phenomena in confined antiferromagnetic systems such as the recent discovered high-T c superconductivity in FeSe films.
Zhiyong Qiu - One of the best experts on this subject based on the ideXlab platform.
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Spin colossal magnetoresistance in an antiferromagnetic insulator
Nature materials, 2018Co-Authors: Zhiyong Qiu, Dazhi Hou, Joseph Barker, Kei Yamamoto, Olena Gomonay, Eiji SaitohAbstract:Colossal magnetoresistance (CMR) refers to a large change in electrical conductivity induced by a magnetic field in the vicinity of a metal-insulator transition and has inspired extensive studies for decades\cite{Ramirez1997, Tokura2006}. Here we demonstrate an analogous spin effect near the Neel Temperature $T_{\rm{N}}$=296 K of the antiferromagnetic insulator \CrO. Using a yttrium iron garnet \YIG/\CrO/Pt trilayer, we injected a spin current from the YIG into the \CrO layer, and collected via the inverse spin Hall effect the signal transmitted in the heavy metal Pt. We observed a change by two orders of magnitude in the transmitted spin current within 14 K of the Neel Temperature. This transition between spin conducting and nonconducting states could be also modulated by a magnetic field in isothermal conditions. This effect, that we term spin colossal magnetoresistance (SCMR), has the potential to simplify the design of fundamental spintronics components, for instance enabling the realization of spin current switches or spin-current based memories.
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spin colossal magnetoresistance in an antiferromagnetic insulator
Nature Materials, 2018Co-Authors: Zhiyong Qiu, Dazhi Hou, Joseph Barker, Kei Yamamoto, Olena Gomonay, Eiji SaitohAbstract:Colossal magnetoresistance (CMR) refers to a large change in electrical conductivity induced by a magnetic field in the vicinity of a metal–insulator transition and has inspired extensive studies for decades1,2. Here we demonstrate an analogous spin effect near the Neel Temperature, TN = 296 K, of the antiferromagnetic insulator Cr2O3. Using a yttrium iron garnet YIG/Cr2O3/Pt trilayer, we injected a spin current from the YIG into the Cr2O3 layer and collected, via the inverse spin Hall effect, the spin signal transmitted into the heavy metal Pt. We observed a two orders of magnitude difference in the transmitted spin current within 14 K of the Neel Temperature. This transition between spin conducting and non-conducting states was also modulated by a magnetic field in isothermal conditions. This effect, which we term spin colossal magnetoresistance (SCMR), has the potential to simplify the design of fundamental spintronics components, for instance, by enabling the realization of spin-current switches or spin-current-based memories.
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electric Neel Temperature determination of an antiferromagnetic insulator film
IEEE International Magnetics Conference, 2015Co-Authors: Zhiyong Qiu, D Hou, Eiji SaitohAbstract:Antiferromagnetism, which manifests as the antiparallel alignment of neighboring magnetic moments, is one of the most important magnetic orderings. Although sharing nearly the same mechanism with ferromagnetism, antiferromagnetism was discovered much later due to the compensated magnetic structure which is of very weak response to magnetic field. Because of the same reason, the characterization of the ordering Temperature and magnetic structure of antiferromagnetic material is much more difficult than that of the ferromagnet, which usually requires higher sensitivity in magnetometry and larger sample volume. When the antiferromagnetic material is made into a geometry with confinement such as ultra-thin film, these measurements are especially challenging. In spite of these difficulties, the research interests of antiferromagetism in thin films have been growing in the last several decades with the motivations not only from commercial applications like exchange bias, but also form the emergence of novel phenomena in confined antiferromagnetic systems such as the recent discovered high-T c superconductivity in FeSe films.
Teruo Ono - One of the best experts on this subject based on the ideXlab platform.
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Temperature dependence of spin hall magnetoresistance across the Neel Temperature of coo
Japanese Journal of Applied Physics, 2020Co-Authors: Kent Oda, Takahiro Moriyama, Teruo Ono, Motoi Kimata, Shuhei KasukawaAbstract:Spin Hall magnetoresistance has been used to probe magnetic moments in magnetic insulator/heavy metal thin films. Here we explore the magnetic field-dependent magnetoresistance and the Temperature-dependent magnetoresistance in a Pt/CoO/Pt trilayer near the Neel Temperature of CoO. The obtained magnetoresistance in an antiferromagnetic phase can be interpreted as SMR whereas the results in a paramagnetic one suggest the additional mechanism other than the conventional SMR.
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resistive detection of the Neel Temperature of cr2o3 thin films
Applied Physics Letters, 2019Co-Authors: Tatsuya Iino, Takahiro Moriyama, Hiroyuki Iwaki, Hikaru Aono, Yu Shiratsuchi, Teruo OnoAbstract:Although bulk magnetic properties of various antiferromagnets have been vigorously studied since long ago, their properties in the form of thin films, which are more relevant to antiferromagnetic spintronic devices, have not been investigated as much. In this work, we characterized the Neel Temperature of Cr2O3 thin films by investigating the Temperature dependence of the spin Hall magnetoresistance in Cr2O3/Pt bilayers. A precise determination of the Neel Temperature was made possible by carefully designing the direction of the magnetic anisotropy in Cr2O3. The results provide a reliable way to determine the Neel Temperature of antiferromagnetic thin films.Although bulk magnetic properties of various antiferromagnets have been vigorously studied since long ago, their properties in the form of thin films, which are more relevant to antiferromagnetic spintronic devices, have not been investigated as much. In this work, we characterized the Neel Temperature of Cr2O3 thin films by investigating the Temperature dependence of the spin Hall magnetoresistance in Cr2O3/Pt bilayers. A precise determination of the Neel Temperature was made possible by carefully designing the direction of the magnetic anisotropy in Cr2O3. The results provide a reliable way to determine the Neel Temperature of antiferromagnetic thin films.
C N Chinnasamy - One of the best experts on this subject based on the ideXlab platform.
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enhanced Neel Temperature in mn ferrite nanoparticles linked to growth rate induced cation inversion
Nanotechnology, 2009Co-Authors: Aria Yang, C N Chinnasamy, J M Greneche, Yajie Chen, Soack Dae Yoon, Zhaohui Chen, Kailin Hsu, Zhuhua Cai, K Ziemer, C VittoriaAbstract:Mn ferrite (MnFe(2)O(4)) nanoparticles, having diameters from 4 to 50 nm, were synthesized using a modified co-precipitation technique in which mixed metal chloride solutions were added to different concentrations of boiling NaOH solutions to control particle growth rate. Thermomagnetization measurements indicated an increase in Neel Temperature corresponding to increased particle growth rate and particle size. The Neel Temperature is also found to increase inversely proportionally to the cation inversion parameter, delta, appearing in the formula (Mn(1-delta)Fe(delta))(tet)[Mn(delta)Fe(2-delta)](oct)O(4). These results contradict previously published reports of trends between Neel Temperature and particle size, and demonstrate the dominance of cation inversion in determining the strength of superexchange interactions and subsequently Neel Temperature in ferrite systems. The particle surface chemistry, structure, and magnetic spin configuration play secondary roles.
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large tunability of Neel Temperature by growth rate induced cation inversion in mn ferrite nanoparticles
Applied Physics Letters, 2009Co-Authors: Aria Yang, C N Chinnasamy, J M Greneche, Yajie Chen, Soack Dae Yoon, Kailin Hsu, C Vittoria, V G HarrisAbstract:The tuning of Neel Temperature by greater than 100 K in nanoparticle Mn-ferrite was demonstrated by a growth-rate-induced cation inversion. Mn-ferrite nanoparticles, having diameters from 4 to 50 nm, were synthesized via coprecipitation synthesis. The Neel Temperature (TN) increased inversely to the cation inversion parameter, δ (i.e., defined as (Mn1−δFeδ)tet[MnδFe2−δ]octO4). Concomitantly, TN increased with increased particle growth rate and particle size. These results unambiguously establish cation inversion as the dominant mechanism in modifying the superexchange leading to enhanced TN. The ability to tailor TN enables greater flexibility in applying nanoparticle ferrites in emerging technologies.
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Neel Temperature enhancement in nanostructured nickel zinc ferrite
Applied Physics Letters, 2005Co-Authors: N Ponpandian, C N Chinnasamy, J M Greneche, A Narayanasamy, N Sivakumar, K Chattopadhyay, Kozo Shinoda, Balachandran Jeyadevan, Kazuyuki TohjiAbstract:The Neel Temperature of Ni0.5Zn0.5Fe2O4 spinel ferrite increases significantly from 538 K in the bulk state to 592 K when the grain size is reduced to 16 nm by milling in a high-energy ball mill. This has been attributed to an increase in the AB superexchange interaction strength due to a possible enhancement in the magnetic ion concentration in the A-site on milling, as is evident from extended x-ray absorption fine structure and in-field Mossbauer measurements. (c) 2005 American Institute of Physics.
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grain size effect on the Neel Temperature and magnetic properties of nanocrystalline nife2o4 spinel
Journal of Magnetism and Magnetic Materials, 2002Co-Authors: C N Chinnasamy, N Ponpandian, A Narayanasamy, Balachandran Jeyadevan, Kazuyuki Tohji, Justin R Joseyphus, K ChattopadhyayAbstract:Nanocrystalline NiFe2O4 spinel ferrites with various grain sizes have been synthesized by ball milling the bulk NiFe2O4. The average grain sizes were estimated from the X-ray line broadening of the (3 1 1) reflection. The Neel Temperatures of NiFe2O4 for various grain sizes were determined by magneto thermogravimetric method. The magnetic behaviour has been explained by combining the effects of changes in cation distribution on milling and finite size scaling. The shift in B-H loops has been correlated to the surface spin effects. The high coercivities observed here may be due to high anisotropies of the milled samples. The Hopkinson peak observed just below the Neel Temperature has been explained by the mathematical formalism given by the Stoner Wohlfarth model.
C Vittoria - One of the best experts on this subject based on the ideXlab platform.
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enhanced Neel Temperature in mn ferrite nanoparticles linked to growth rate induced cation inversion
Nanotechnology, 2009Co-Authors: Aria Yang, C N Chinnasamy, J M Greneche, Yajie Chen, Soack Dae Yoon, Zhaohui Chen, Kailin Hsu, Zhuhua Cai, K Ziemer, C VittoriaAbstract:Mn ferrite (MnFe(2)O(4)) nanoparticles, having diameters from 4 to 50 nm, were synthesized using a modified co-precipitation technique in which mixed metal chloride solutions were added to different concentrations of boiling NaOH solutions to control particle growth rate. Thermomagnetization measurements indicated an increase in Neel Temperature corresponding to increased particle growth rate and particle size. The Neel Temperature is also found to increase inversely proportionally to the cation inversion parameter, delta, appearing in the formula (Mn(1-delta)Fe(delta))(tet)[Mn(delta)Fe(2-delta)](oct)O(4). These results contradict previously published reports of trends between Neel Temperature and particle size, and demonstrate the dominance of cation inversion in determining the strength of superexchange interactions and subsequently Neel Temperature in ferrite systems. The particle surface chemistry, structure, and magnetic spin configuration play secondary roles.
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large tunability of Neel Temperature by growth rate induced cation inversion in mn ferrite nanoparticles
Applied Physics Letters, 2009Co-Authors: Aria Yang, C N Chinnasamy, J M Greneche, Yajie Chen, Soack Dae Yoon, Kailin Hsu, C Vittoria, V G HarrisAbstract:The tuning of Neel Temperature by greater than 100 K in nanoparticle Mn-ferrite was demonstrated by a growth-rate-induced cation inversion. Mn-ferrite nanoparticles, having diameters from 4 to 50 nm, were synthesized via coprecipitation synthesis. The Neel Temperature (TN) increased inversely to the cation inversion parameter, δ (i.e., defined as (Mn1−δFeδ)tet[MnδFe2−δ]octO4). Concomitantly, TN increased with increased particle growth rate and particle size. These results unambiguously establish cation inversion as the dominant mechanism in modifying the superexchange leading to enhanced TN. The ability to tailor TN enables greater flexibility in applying nanoparticle ferrites in emerging technologies.
