Anisotropic magnetoresistance(AMR)and related planar Hall resistance(PHR)are ubiquitous phenomena of magnetic materials.Although the universal angular dependences of AMR and PHR in magnetic polycrystalline materials w...Anisotropic magnetoresistance(AMR)and related planar Hall resistance(PHR)are ubiquitous phenomena of magnetic materials.Although the universal angular dependences of AMR and PHR in magnetic polycrystalline materials with one order parameter are well known,no similar universal relation for other class of magnetic materials are known to date.Here a general theory of galvanomagnetic effects in magnetic materials is presented with two vector order parameters,such as magnetic single crystals with a dominated crystalline axis or polycrystalline non-collinear ferrimagnetic materials.It is shown that AMR and PHR have a universal angular dependence.In general,both longitudinal and transverse resistivity are non-reciprocal in the absence of inversion symmetry:Resistivity takes different values when the current is reversed.Different from simple magnetic polycrystalline materials where AMR and PHR have the same magnitude,and π/4 out of phase,the magnitudes of AMR and PHR of materials with two vector order parameters are not the same in general,and the phase difference is not π/4.Instead ofπperiodicity of the usual AMR and PHR,the periodicities of materials with two order parameters are 2π.展开更多
Based on the findings of skyrmion nature of stripes and the metastability of a state of an arbitrary number of skyrmions,precisely controlled manipulation of stripes of skyrmion number 1 in pre-designed structures and...Based on the findings of skyrmion nature of stripes and the metastability of a state of an arbitrary number of skyrmions,precisely controlled manipulation of stripes of skyrmion number 1 in pre-designed structures and mutual transformation between helical states and skyrmion crystals(Sk Xs)are demonstrated in chiral magnetic films.As a proof of the concept,we show how to use patterned magnetic fields and spin-transfer torques(STTs)to generate nematic and smectic stripe phases,as well as“UST”mosaic from three curved stripes.Cutting one stripe into many pieces and coalescing several skyrmions into one by various external fields are good ways to transform helical states and Sk Xs from each other.展开更多
基金supported by the National Key Research and Development Program of China(Grant Nos.2020YFA0309600 and 2018YFB0407600)the National Natural Science Foundation of China(Grant Nos.11974296 and 11774296)Hong Kong RGC(Grant Nos.16301518,16301619,and 16302321)。
文摘Anisotropic magnetoresistance(AMR)and related planar Hall resistance(PHR)are ubiquitous phenomena of magnetic materials.Although the universal angular dependences of AMR and PHR in magnetic polycrystalline materials with one order parameter are well known,no similar universal relation for other class of magnetic materials are known to date.Here a general theory of galvanomagnetic effects in magnetic materials is presented with two vector order parameters,such as magnetic single crystals with a dominated crystalline axis or polycrystalline non-collinear ferrimagnetic materials.It is shown that AMR and PHR have a universal angular dependence.In general,both longitudinal and transverse resistivity are non-reciprocal in the absence of inversion symmetry:Resistivity takes different values when the current is reversed.Different from simple magnetic polycrystalline materials where AMR and PHR have the same magnitude,and π/4 out of phase,the magnitudes of AMR and PHR of materials with two vector order parameters are not the same in general,and the phase difference is not π/4.Instead ofπperiodicity of the usual AMR and PHR,the periodicities of materials with two order parameters are 2π.
基金supported by the National Key Research and Development Program of China(Grant Nos.2018YFB0407600,and 2020YFA0309600)the National Natural Science Foundation of China(Grant Nos.11974296+2 种基金11774296)Hong Kong Research Grant Council(Grant Nos.16301518,and 16301619)。
文摘Based on the findings of skyrmion nature of stripes and the metastability of a state of an arbitrary number of skyrmions,precisely controlled manipulation of stripes of skyrmion number 1 in pre-designed structures and mutual transformation between helical states and skyrmion crystals(Sk Xs)are demonstrated in chiral magnetic films.As a proof of the concept,we show how to use patterned magnetic fields and spin-transfer torques(STTs)to generate nematic and smectic stripe phases,as well as“UST”mosaic from three curved stripes.Cutting one stripe into many pieces and coalescing several skyrmions into one by various external fields are good ways to transform helical states and Sk Xs from each other.
