Anomalous Nernst Effect and Its Implications for Time-Reversal Symmetry Breaking in Kagome Metal ScV6Sn6

TL;DR

This paper reports the discovery of anomalous Nernst signals in the nonmagnetic kagome metal ScV6Sn6, indicating possible time-reversal symmetry breaking and hidden magnetism, with implications for understanding unconventional charge order.

Contribution

It reveals unconventional anomalous thermoelectric effects and suggests time-reversal symmetry breaking in ScV6Sn6, a nonmagnetic kagome metal, expanding knowledge of hidden magnetic phenomena.

Findings

Anomalous Nernst signals peak near 92 K

Persistent signals in charge-ordered state down to 10 K

Field-dependent thermopower and thermal conductivity changes

Abstract

The nonmagnetic kagome metal ScV6Sn6 displays an unconventional charge order (CO) accompanied by signatures of an anomalous Hall effect, hidden magnetism, and multiple lattice instabilities. In this study, we report the observation of unconventional anomalous thermoelectric properties. Notably, unexpected anomalous transverse Nernst signals reach a peak value of ~4 {\mu}V/K near the TCDW ~92 K in ScV6Sn6, and these signals persist in the charge-ordered state as the temperature decreases to 10 K. Furthermore, both thermopower and thermal conductivity exhibit significant changes under magnetic fields, even in the nonmagnetic ground state. These observations strongly suggest the emergence of time-reversal symmetry breaking in ScV6Sn6, as supported by muon spin relaxation ({\mu}SR) measurements. While hidden magnetism represents the most plausible origin, alternative mechanisms involving orbital currents and chiral charge order remain possible.