Speaker
Description
In recent years, there has been an influx of research surrounding the kagome AV$_3$Sb$_5$ (A = K, Rb, Cs) compounds which display both superconductivity and charge order [1,2]. The onset of charge order has been associated with the breaking of time-reversal symmetry (TRS), but the extent to which TRS breaking can be tuned is relatively unexplored. To address this, we employ muon spin rotation and local field analysis to explore the evolution of TRS breaking as a function of depth in three AV$_3$Sb$_5$ derived compounds [3,4]:
(1) RbV$_3$Sb$_5$ with charge order, T$_\mathrm{CO}$ = 100 K
(2) Cs(V$_{0.93}$Nb$_{0.07}$)$_3$Sb$_5$ with partially suppressed charge order, T$_\mathrm{CO}$ = 58 K
(3) Cs(V$_{0.86}$Ta$_{0.14}$)$_3$Sb$_5$ with fully suppressed charge order
Our results show a clear increase of the muon spin relaxation rate when charge order is present, indicating the onset of TRS breaking. This signal can be further enhanced on approaching the surface, with a clear correlation emerging between the strength of charge order and onset temperature, T$_\mathrm{CO}$. We also remark on a curious decoupling of TRS breaking from T$_\mathrm{CO}$ near the surface, which mirrors behaviour observed in high-temperature cuprate superconductors indicating the presence of potential orbital currents [5].
[1] B. R. Ortiz et al. Phys. Rev. Mater. 3, 094407 (2019),
[2] Z. Guguchia, R. Khasanov, H. Luetkens, NPJ Quantum Materials 8, 41 (2023),
[3] J. N. Graham et al. Nat. Commun. 15, 8978 (2024),
[4] J. N. Graham et al. arXiv:2411.18744 (2024),
[5] B. Keimer et al. Nature 518, 179 (2015)
| jennifer.graham@psi.ch | |
| Funding Agency | SNSF Starting Grant (No. TMSGI2_211750) |
| Supervisors Name | Zurab Guguchia |
| Supervisors Email | zurab.guguchia@psi.ch |
| Did you request an Invitation Letter for a Visitors Visa Application | No |
