Extremely large magnetoresistance(XMR)has been explored in many nonmagnetic topologically nontrivial/trivial semimetals,while it is experimentally ambiguous which mechanism should be responsible in a specific material...Extremely large magnetoresistance(XMR)has been explored in many nonmagnetic topologically nontrivial/trivial semimetals,while it is experimentally ambiguous which mechanism should be responsible in a specific material due to the complex electronic structures.In this paper,the magnetoresistance origin of single crystal CaAl4 with C2/m structure at low temperature is investigated,exhibiting unsaturated magnetoresistance of~3000%at 2.5 K and 14 T as the fingerprints of XMR materials.By the combination of ARPES and the first-principles calculations,we elaborate multiband features and anisotropic Fermi surfaces,which can explain the mismatch of isotropic two-band model.Although the structural phase transition from I4/mmm to C2/m has been recognized,the subtle impact on electronic structure is revealed by our ARPES measurements.Considering that both charge compensation and potential topologically nontrivial band structure exist in CaAl4,our findings report CaAl4 as a new reference material for exploring the XMR phenomena.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11774421, 12074425, 11874422, 11574391, and 11774424)the National Key Research and Development Program of China (Grant No. 2019YFA0308602)+1 种基金the Fundamental Research Funds for the Central Universities,Chinathe Research Funds of Renmin University of China (Grant Nos. 19XNLG13, 18XNLG14, and 19XNLG18)
文摘Extremely large magnetoresistance(XMR)has been explored in many nonmagnetic topologically nontrivial/trivial semimetals,while it is experimentally ambiguous which mechanism should be responsible in a specific material due to the complex electronic structures.In this paper,the magnetoresistance origin of single crystal CaAl4 with C2/m structure at low temperature is investigated,exhibiting unsaturated magnetoresistance of~3000%at 2.5 K and 14 T as the fingerprints of XMR materials.By the combination of ARPES and the first-principles calculations,we elaborate multiband features and anisotropic Fermi surfaces,which can explain the mismatch of isotropic two-band model.Although the structural phase transition from I4/mmm to C2/m has been recognized,the subtle impact on electronic structure is revealed by our ARPES measurements.Considering that both charge compensation and potential topologically nontrivial band structure exist in CaAl4,our findings report CaAl4 as a new reference material for exploring the XMR phenomena.
