Nanowerk August 14, 2023
The Berry curvature and quantum metric are the imaginary part and real part, respectively, of the quantum geometric tensor which characterizes the topology of quantum states. The former is known to generate a zoo of important discoveries such as quantum Hall effect and anomalous Hall effect (AHE), while the consequences of the quantum metric have rarely been probed by transport. An international team of researchers (Singapore, Israel, China, Japan) has found quantum metric-induced nonlinear transport, including both nonlinear AHE and diode-like nonreciprocal longitudinal response, in thin films of a topological antiferromagnet, MnBi2Te4. They have revealed that the transverse and longitudinal nonlinear conductivities reverse signs when reversing the antiferromagnetic order, diminish above the Néel temperature, and are insensitive to disorder scattering, thus verifying their origin in the band structure topology. They flipped signs between electron and hole-doped regions, in agreement with theoretical calculations. According to the researchers their work provides a pathway to probe the quantum metric through nonlinear transport and to design magnetic nonlinear devices… read more.Â
TECHNICAL ARTICLE
…The lines radiating from the center are electrodes from which current was passed through the manganese bismuth telluride. Credit: NTU Singapore