High Resolution Polar Kerr Effect Studies of Cs3Sb5 and ScV6Sn6 Below the Charge Order Transition

TL;DR

This study used high-resolution polar Kerr effect measurements to investigate potential spontaneous magnetic order in CsV3Sb5 and ScV6Sn6 below their charge order transitions, finding no evidence of such order within detection limits.

Contribution

It provides the first high-resolution Kerr effect measurements on these materials, setting stringent limits on possible spontaneous magnetic order associated with charge density waves.

Findings

No zero-field Kerr signal detected within 100 nanoradians.

Charge order transition is sharp and well-defined.

Strain application did not induce detectable Kerr effect.

Abstract

We report high resolution polar Kerr effect measurements on CsV3Sb5 and ScV6Sn6 single crystals in search for signatures of spontaneous polar Kerr effect (PKE) below the charge order transitions of these materials. Utilizing two separate zero-area loop Sagnac interferometers operating at 1550 nm and 830 nm wavelengths, we studied the temperature dependence of possible PKE after training with magnetic field. While a finite field Kerr measurement yielded optical rotation expected from the Pauli susceptibility of the itinerant carriers, no signal was detected at zero-field to within the noise floor limit of the apparatus of below $\sim$100 nanoradians. Simultaneous coherent reflection measurements confirm the sharpness of the charge order transition in the same optical volume as the Kerr measurements. Application of strain to reveal a hidden flux-ordered magnetic state did not result in a finite Kerr effect.