Probing orbital magnetism of a kagome metal CsV3Sb5 by a tuning fork resonator

TL;DR

This study investigates the magnetic properties of the kagome metal CsV3Sb5, revealing a highly anisotropic, slow-dynamics magnetic phase below 30 K that likely breaks time-reversal symmetry with an unconventional origin.

Contribution

It introduces tuning fork resonator measurements to probe the orbital magnetism and uncovers a novel, highly anisotropic magnetic state in CsV3Sb5 below 30 K.

Findings

Detected a cascade of phase transitions in the CDW phase.

Identified a highly anisotropic magnetic structure below 30 K.

Observed slow magnetic dynamics and small saturation field.

Abstract

The recently discovered kagome metal CsV$_3$Sb$_5$ exhibits a complex phase diagram that encompasses frustrated magnetism, topological charge density wave (CDW), and superconductivity. One CDW state that breaks time-reversal symmetry was proposed in this compound, while the exact nature of the putative magnetic state remains elusive. To examine the thermodynamic state of CsV$_3$Sb$_5$ and assess the character of the associated magnetism, we conducted tuning fork resonator measurements of magnetotropic susceptibility over a broad range of angles, magnetic fields, and temperature. We found a cascade of phase transition in the CDW phase. Of particular interest is a highly anisotropic magnetic structure that arises below about 30~K, with a magnetic moment along the $c$-axis that has an extremely small magnitude. This magnetic state demonstrates extremely slow dynamics and small saturate field, all suggest that electronic phase below 30~K breaks time reversal symmetry and has an unconventional origin.