We theoretically and experimentally studied the Gilbert damping evolution of both acoustic and optical magnetic resonance modes in the layered flake Cr Cl;with an external magnetic field H applied in plane.Based on a ...We theoretically and experimentally studied the Gilbert damping evolution of both acoustic and optical magnetic resonance modes in the layered flake Cr Cl;with an external magnetic field H applied in plane.Based on a Lagrangian equation and a Rayleigh dissipation function,we predicted that the resonance linewidth△H as a function of microwave frequencyωis nonlinear for both acoustic and optical modes in the Cr Cl;flake,which is significantly different from the linear relationship of△H-ωin ferromagnets.Measuring the microwave transmission through the Cr Cl;flake,we obtained theω–H dispersion and damping evolution△H–ωfor both acoustic and optical modes.Combining both our theoretical prediction and experimental observations,we concluded that the nonlinear damping evolution△H–ωis a consequence of the interlayer interaction during the antiferromagnetic resonance,and the interlayer Gilbert dissipation plays an important role in the nonlinear damping evolution because of the asymmetry of the non-collinear magnetizaiton between layers.展开更多
We experimentally and theoretically investigate the microwave transmission line shape of the cavity-magnon-polariton(CMP)created by inserting a low damping magnetic insulator into a high quality 3D microwave cavity. W...We experimentally and theoretically investigate the microwave transmission line shape of the cavity-magnon-polariton(CMP)created by inserting a low damping magnetic insulator into a high quality 3D microwave cavity. While fixed field measurements are found to have the expected Lorentzian characteristic, at fixed frequencies the field swept line shape is in general asymmetric. Such fixed frequency measurements demonstrate that microwave transmission can be used to access magnetic characteristics of the CMP,such as the field line width H. By developing an effective oscillator model of the microwave transmission we show that these line shape features are general characteristics of harmonic coupling. At the same time, at the classical level the underlying physical mechanism of the CMP is electrodynamic phase correlation and a second model based on this principle also accurately reproduces the experimental line shape features. In order to understand the microscopic origin of the effective coupled oscillator model and to allow for future studies of CMP phenomena to extend into the quantum regime, we develop a third, microscopic description,based on a Green's function formalism. Using this method we calculate the transmission spectra and find good agreement with the experimental results.展开更多
Material functionalities strongly depend on the stoichiometry,crystal structure,and homogeneity.Here we demonstrate an approach of amorphous nonstoichiometric inhomogeneous oxides to realize tunable ferromagnetism and...Material functionalities strongly depend on the stoichiometry,crystal structure,and homogeneity.Here we demonstrate an approach of amorphous nonstoichiometric inhomogeneous oxides to realize tunable ferromagnetism and electrical transport at room temperature.In order to verify the origin of the ferromagnetism,we employed a series of structural,chemical,and electronic state characterizations.Combined with electron microscopy and transport measurements,synchrotron-based grazing incident wide angle X-ray scattering,soft X-ray absorption and circular dichroism clearly reveal that the roomtemperature ferromagnetism originates from the In0.23Co0.77O1-v,amorphous phase with a large tunable range of oxygen vacancies.The room-temperature ferromagnetism is tunable from a high saturation magnetization of 500 emu cm-3 to below 25 emu cm-3,with the evolving electrical resistivity from5×103μΩ cm to above 2.5×105 μΩ cm.Inhomogeneous nano-crystallization emerges with decreasing oxygen vacancies,driving the system towards non-ferromagnetism and insulating regime.Our work unfolds the novel functionalities of amorphous nonstoichiometric inhomogeneous oxides,which opens up new opportunities for developing spintronic materials with superior magnetic and transport properties.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11774200)the Shandong Provincial Natural Science Foundation,China(Grant No.ZR2019JQ02)the Youth Interdisciplinary Science and Innovative Research Groups of Shandong University。
文摘We theoretically and experimentally studied the Gilbert damping evolution of both acoustic and optical magnetic resonance modes in the layered flake Cr Cl;with an external magnetic field H applied in plane.Based on a Lagrangian equation and a Rayleigh dissipation function,we predicted that the resonance linewidth△H as a function of microwave frequencyωis nonlinear for both acoustic and optical modes in the Cr Cl;flake,which is significantly different from the linear relationship of△H-ωin ferromagnets.Measuring the microwave transmission through the Cr Cl;flake,we obtained theω–H dispersion and damping evolution△H–ωfor both acoustic and optical modes.Combining both our theoretical prediction and experimental observations,we concluded that the nonlinear damping evolution△H–ωis a consequence of the interlayer interaction during the antiferromagnetic resonance,and the interlayer Gilbert dissipation plays an important role in the nonlinear damping evolution because of the asymmetry of the non-collinear magnetizaiton between layers.
基金supported by the Natural Sciences and Engineering Research Council of Canada (NSERC)-Canada Graduate Scholarships-Doctoral Program, the NSERC (Jesko Sirker and Can-Ming Hu)the National Natural Science Foundation of China (Grant No. 11429401)the Canada Foundation for Innovation and Canadian Microelectronics Corporation Grants (Can Ming Hu)
文摘We experimentally and theoretically investigate the microwave transmission line shape of the cavity-magnon-polariton(CMP)created by inserting a low damping magnetic insulator into a high quality 3D microwave cavity. While fixed field measurements are found to have the expected Lorentzian characteristic, at fixed frequencies the field swept line shape is in general asymmetric. Such fixed frequency measurements demonstrate that microwave transmission can be used to access magnetic characteristics of the CMP,such as the field line width H. By developing an effective oscillator model of the microwave transmission we show that these line shape features are general characteristics of harmonic coupling. At the same time, at the classical level the underlying physical mechanism of the CMP is electrodynamic phase correlation and a second model based on this principle also accurately reproduces the experimental line shape features. In order to understand the microscopic origin of the effective coupled oscillator model and to allow for future studies of CMP phenomena to extend into the quantum regime, we develop a third, microscopic description,based on a Green's function formalism. Using this method we calculate the transmission spectra and find good agreement with the experimental results.
基金supported by the National Natural Science Foundation of China (11434006, 11774199, and 51871112)the National Basic Research Program of China (2015CB921502)+1 种基金the 111 Project B13029supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DEAC02-76SF00515。
文摘Material functionalities strongly depend on the stoichiometry,crystal structure,and homogeneity.Here we demonstrate an approach of amorphous nonstoichiometric inhomogeneous oxides to realize tunable ferromagnetism and electrical transport at room temperature.In order to verify the origin of the ferromagnetism,we employed a series of structural,chemical,and electronic state characterizations.Combined with electron microscopy and transport measurements,synchrotron-based grazing incident wide angle X-ray scattering,soft X-ray absorption and circular dichroism clearly reveal that the roomtemperature ferromagnetism originates from the In0.23Co0.77O1-v,amorphous phase with a large tunable range of oxygen vacancies.The room-temperature ferromagnetism is tunable from a high saturation magnetization of 500 emu cm-3 to below 25 emu cm-3,with the evolving electrical resistivity from5×103μΩ cm to above 2.5×105 μΩ cm.Inhomogeneous nano-crystallization emerges with decreasing oxygen vacancies,driving the system towards non-ferromagnetism and insulating regime.Our work unfolds the novel functionalities of amorphous nonstoichiometric inhomogeneous oxides,which opens up new opportunities for developing spintronic materials with superior magnetic and transport properties.
