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
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.
