Exchange coupling across the interface between a ferromagnetic(FM)layer and an antiferromagnetic(AFM)or another FM layer may induce a unidirectional magnetic anisotropy and/or a uniaxial magnetic anisotropy,which has ...Exchange coupling across the interface between a ferromagnetic(FM)layer and an antiferromagnetic(AFM)or another FM layer may induce a unidirectional magnetic anisotropy and/or a uniaxial magnetic anisotropy,which has been extensively studied due to the important application in magnetic materials and devices.In this work,we observed a fourfold magnetic anisotropy in amorphous Co Fe B layer when exchange coupling to an adjacent Fe Rh layer which is epitaxially grown on an SrTiO_(3)(001)substrate.As the temperature rises from 300 K to 400 K,Fe Rh film undergoes a phase transition from AFM to FM phase,the induced fourfold magnetic anisotropy in the Co Fe B layer switches the orientation from the Fe Rh<110>to Fe Rh<100>directions and the strength is obviously reduced.In addition,the effective magnetic damping as well as the two-magnon scattering of the Co Fe B/Fe Rh bilayer also remarkably increase with the occurrence of magnetic phase transition of Fe Rh.No exchange bias is observed in the bilayer even when Fe Rh is in the nominal AFM state,which is probably because the residual FM Fe Rh moments located at the interface can well separate the exchange coupling between the below pinned Fe Rh moments and the Co Fe B moments.展开更多
The REAl(Si,Ge)(RE=rare earth)family,known to break both the inversion-and time-reversal symmetries,represents one of the most suitable platforms for investigating the interplay between correlated-electron phenomena a...The REAl(Si,Ge)(RE=rare earth)family,known to break both the inversion-and time-reversal symmetries,represents one of the most suitable platforms for investigating the interplay between correlated-electron phenomena and topologically nontrivial bands.Here,we report on systematic magnetic,transport,and muon-spin rotation and relaxation(μSR)measurements on(Nd,Sm)AlGe single crystals,which exhibit antiferromagnetic(AFM)transitions at T_(N)=6.1 and 5.9 K,respectively.In addition,NdAlGe undergoes also an incommensurate-to-commensurate ferrimagnetic transition at 4.5 K.Weak transverse-fieldμSR measurements confirm the AFM transitions,featuring a~90%magnetic volume fraction.Zero-field(ZF)μSR measurements reveal a more disordered internal field distribution in NdAlGe than in SmAlGe,reflected in a larger transverse muon-spin relaxation rateλTat T<<T_(N).This may be due to the complex magnetic structure of NdAlGe,which undergoes a series of metamagnetic transitions in an external magnetic field,while SmAlGe shows only a robust AFM order.In NdAlGe,the topological Hall effect(THE)appears between the first and the second metamagnetic transitions for H‖c,while it is absent in SmAlGe.Such THE in NdAlGe is most likely attributed to the field-induced topological spin textures.The longitudinal muon-spin relaxation rateλL,diverges near the AFM order,followed by a clear drop at T<T_N.In the magnetically ordered state,spin fluctuations are significantly stronger in NdAlGe than in SmAlGe.In general,our longitudinal-fieldμSR data indicate vigorous spin fluctuations in NdAlGe,thus providing valuable insights into the origin of THE and of the possible topological spin textures in REAl(Si,Ge)Weyl semimetals.展开更多
We report the discovery of a new noncentrosymmetric superconductor CaPtAs.It crystallizes in a tetragonal structure(space group I41md,No.109),featuring three dimensional honeycomb networks of Pt-As and a much elongate...We report the discovery of a new noncentrosymmetric superconductor CaPtAs.It crystallizes in a tetragonal structure(space group I41md,No.109),featuring three dimensional honeycomb networks of Pt-As and a much elongated c-axis(a=b=4.18?,and c=43.70?).The superconductivity of CaPtAs with Tc=1.47 K was characterized by means of electrical resistivity,specific heat,and ac magnetic susceptibility.The electronic specific heat Ce(T)/T shows evidence for a deviation from the behavior of a conventional BCS superconductor,and can be reasonably fitted by a p-wave model.The upper critical fieldμ0Hc2 of CaPtAs exhibits a moderate anisotropy,with an in-plane value of around 204 mT and an out-of-plane value of 148 mT.Density functional theory calculations indicate that the Pt-5 d and As-4 p orbitals mainly contribute to the density of states near the Fermi level,showing that the Pt-As honeycomb networks may significantly influence the superconducting properties.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874150,51871233,and 12174103)the Natural Science Foundation of Shanghai(Grant Nos.21ZR1420500 and 21JC1402300)。
文摘Exchange coupling across the interface between a ferromagnetic(FM)layer and an antiferromagnetic(AFM)or another FM layer may induce a unidirectional magnetic anisotropy and/or a uniaxial magnetic anisotropy,which has been extensively studied due to the important application in magnetic materials and devices.In this work,we observed a fourfold magnetic anisotropy in amorphous Co Fe B layer when exchange coupling to an adjacent Fe Rh layer which is epitaxially grown on an SrTiO_(3)(001)substrate.As the temperature rises from 300 K to 400 K,Fe Rh film undergoes a phase transition from AFM to FM phase,the induced fourfold magnetic anisotropy in the Co Fe B layer switches the orientation from the Fe Rh<110>to Fe Rh<100>directions and the strength is obviously reduced.In addition,the effective magnetic damping as well as the two-magnon scattering of the Co Fe B/Fe Rh bilayer also remarkably increase with the occurrence of magnetic phase transition of Fe Rh.No exchange bias is observed in the bilayer even when Fe Rh is in the nominal AFM state,which is probably because the residual FM Fe Rh moments located at the interface can well separate the exchange coupling between the below pinned Fe Rh moments and the Co Fe B moments.
基金supported by the Natural Science Foundation of Shanghai(Grant Nos.21ZR1420500,and 21JC1402300)the Natural Science Foundation of Chongqing(Grant No.CSTB-2022NSCQ-MSX1678)+3 种基金the National Natural Science Foundation of China(Grant Nos.12374105,and 12350710785)the Fundamental Research Funds for the Central Universitiesthe Schweizerische Nationalfonds zur F?rderung der Wissenschaftlichen Forschung(SNF)(Grant Nos.200021169455,and 200021188706)support from Paul Scherrer Institute Research Grant(Grant No.202101346)。
文摘The REAl(Si,Ge)(RE=rare earth)family,known to break both the inversion-and time-reversal symmetries,represents one of the most suitable platforms for investigating the interplay between correlated-electron phenomena and topologically nontrivial bands.Here,we report on systematic magnetic,transport,and muon-spin rotation and relaxation(μSR)measurements on(Nd,Sm)AlGe single crystals,which exhibit antiferromagnetic(AFM)transitions at T_(N)=6.1 and 5.9 K,respectively.In addition,NdAlGe undergoes also an incommensurate-to-commensurate ferrimagnetic transition at 4.5 K.Weak transverse-fieldμSR measurements confirm the AFM transitions,featuring a~90%magnetic volume fraction.Zero-field(ZF)μSR measurements reveal a more disordered internal field distribution in NdAlGe than in SmAlGe,reflected in a larger transverse muon-spin relaxation rateλTat T<<T_(N).This may be due to the complex magnetic structure of NdAlGe,which undergoes a series of metamagnetic transitions in an external magnetic field,while SmAlGe shows only a robust AFM order.In NdAlGe,the topological Hall effect(THE)appears between the first and the second metamagnetic transitions for H‖c,while it is absent in SmAlGe.Such THE in NdAlGe is most likely attributed to the field-induced topological spin textures.The longitudinal muon-spin relaxation rateλL,diverges near the AFM order,followed by a clear drop at T<T_N.In the magnetically ordered state,spin fluctuations are significantly stronger in NdAlGe than in SmAlGe.In general,our longitudinal-fieldμSR data indicate vigorous spin fluctuations in NdAlGe,thus providing valuable insights into the origin of THE and of the possible topological spin textures in REAl(Si,Ge)Weyl semimetals.
基金the National Key R&D Program of China(Grant Nos.2016YFA0300202,and 2017YFA0303100)the National Natural Science Foundation of China(Grant Nos.U1632275,and 11874320)+1 种基金the Science Challenge Project of China(Grant No.TZ2016004)the Fundamental Research Funds for the Central Universities.
文摘We report the discovery of a new noncentrosymmetric superconductor CaPtAs.It crystallizes in a tetragonal structure(space group I41md,No.109),featuring three dimensional honeycomb networks of Pt-As and a much elongated c-axis(a=b=4.18?,and c=43.70?).The superconductivity of CaPtAs with Tc=1.47 K was characterized by means of electrical resistivity,specific heat,and ac magnetic susceptibility.The electronic specific heat Ce(T)/T shows evidence for a deviation from the behavior of a conventional BCS superconductor,and can be reasonably fitted by a p-wave model.The upper critical fieldμ0Hc2 of CaPtAs exhibits a moderate anisotropy,with an in-plane value of around 204 mT and an out-of-plane value of 148 mT.Density functional theory calculations indicate that the Pt-5 d and As-4 p orbitals mainly contribute to the density of states near the Fermi level,showing that the Pt-As honeycomb networks may significantly influence the superconducting properties.
