Phys. Rev. B 109, 155121 (2024)

A wide array of unusual phenomena has recently been uncovered in kagome solids. The charge density wave (CDW) state in the kagome superconductor ${A\mathrm{V}}_3{\mathrm{Sb}}_5$, in particular, intrigued the community; the CDW phase appears to break the time-reversal symmetry despite the absence of spin magnetism, which has been tied to exotic orbital loop currents possibly intertwined with magnetic field tunable crystal distortions. To test this connection, precise determination of the lattice response to an applied magnetic field is crucial but can be challenging at the atomic scale. We establish a scanning tunneling microscopy (STM) based method to study the evolution of the ${A\mathrm{V}}_3{\mathrm{Sb}}_5$ atomic structure as a function of magnetic field. The method substantially reduces the errors of typical STM measurements, which are at the order of 1% when measuring an in-plane lattice constant change. We find that the out-of-plane lattice constant of ${A\mathrm{V}}_3{\mathrm{Sb}}_5$ remains unchanged (within ${10}^{-6}$) by the application of both in-plane and out-of-plane magnetic fields. We also reveal that the in-plane lattice response to magnetic field is at most at the order of 0.05%. Our experiments provide further constraints on time-reversal symmetry breaking in kagome metals and establish a tool for higher-resolution extraction of the field-lattice coupling at the nanoscale applicable to other quantum materials.

• Received 7 November 2023
• Revised 12 February 2024
• Accepted 13 March 2024

DOI:https://doi.org/10.1103/PhysRevB.109.155121

Condensed Matter, Materials & Applied Physics