Experiment Unveils Berry Curvature Dominated Linear Positive Magnetoresistance
On Nov. 2, Proceedings of the National Academy of Sciences of the United States of America, PNAS, published a research entitled "Scaling of Berry-curvature monopole dominated large linear positive magnetoresistance" online. The research group lead by Prof. LIU Enke from the Institute of Physics, Chinese Academy of Sciences, established a physical model about Berry curvature dominated linear positive magnetoresistance (LPMR), and provided experimental evidence for this mechanism.
Berry curvature, the pseudomagnetic field in momentum space, is the origin of many transport phenomena including chiral anomaly and intrinsic anomalous transverse transport properties. In topological materials, Berry curvature is extremely large because of special band structures, e.g., Dirac nodes, Weyl nodes, and nodal lines. LPMR is a transport phenomenon that longitudinal resistance of a material varies linearly and positively with magnetic field. Large LPMR was widely reported in topological materials.
However, explanations for large LPMR in topological materials are ambiguous. Researchers in LIU's group and their collaborators, studied the relation between Berry curvature and LPMR based on a topological material candidate, CoS2. Their research shows, in theory, the slope of LPMR is proportional to the average of Berry curvature around the Fermi surface. They proposed temperature-dependent anomalous Hall conductivity and LPMR equations based on a 3D-Weyl-node model. The experiment data of CoS2 and other topological materials reported previously can be fitted by the theoretical temperature-dependent equations, which is an evidence for the Berry curvature dominated LPMR.
This research unveiled the relation between Berry curvature and LPMR, and promoted the common understanding and functional designing of the LPMR materials for magnetic sensing or information storage.
The study was supported by the National Science Foundation, the Ministry of Science and Technology of China, the Chinese Academy of Sciences (the Strategic Priority Research Program (B), CAS President's International Fellowship Initiative for Distinguished Scientists).
Fig.1 The schematic illustration of Berry curvature induced LPMR and the fitting of experimental data to theoretical equations. (Image by Institute of Physics)
Institute of Physics
topological materials, Berry curvature, linear magnetoresistance
Explanations for large linear positive magnetoresistance observed in topological materials are ambiguous. This research established the relation between Berry curvature and LPMR theoretically and experimentally.