Topological charge-entropy scaling in kagome Chern magnet TbMn6Sn6

Abstract

In ordinary materials, electrons conduct both electricity and heat, where their charge-entropy relations observe the Mott formula and the Wiedemann-Franz law. In topological quantum materials, the transverse motion of relativistic electrons can be strongly affected by the quantum field arising around the topological fermions, where a simple model description of their charge-entropy relations remains elusive. Here we report the topological charge-entropy scaling in the kagome Chern magnet TbMn6Sn6, featuring pristine Mn kagome lattices with strong out-of-plane magnetization. Through both electric and thermoelectric transports, we observe quantum oscillations with a nontrivial Berry phase, a large Fermi velocity and two-dimensionality, supporting the existence of Dirac fermions in the magnetic kagome lattice. This quantum magnet further exhibits large anomalous Hall, anomalous Nernst, and anomalous thermal Hall effects, all of which persist to above room temperature. Remarkably, we show that the charge-entropy scaling relations of these anomalous transverse transports can be ubiquitously described by the Berry curvature field effects in a Chern-gapped Dirac model. Our work points to a model kagome Chern magnet for the proof-of-principle elaboration of the topological charge-entropy scaling.

Highly anisotropic magnetism in the vanadium-based kagome metal TbV6Sn6

“…A weak, low-field departure from a conventional twoband model below T C likely corresponds to the onset of the anomalous Hall effect in TbV 6 Sn 6 , although it is difficult to reliably isolate the contribution given the small hysteresis of the ferromagnetic state and the added complication of a two-band transport background. The absence of the stronger molecular field created by magnetic 3d transition metal ions on the kagome lattice softens the ordered state, and future studies isolating the anomalous Hall component will provide an interesting comparison to the quantum-limit Chern magnetism reported in TbMn 6 Sn 6 [24,25]. Furthermore, by isolating the magnetic order within Tb planes TbV 6 Sn 6 affords independent control of the anisotropy and the character of magnetic order via alloying the R-site while retaining the electronic structure of the nonmagnetic V-kagome layers.…”

“…within kagome metals seemingly validates their promise as hosts of a rich frontier of unconventional ground states and phase behaviors. In particular, kagome metals that crystallize in the MgFe 6 Ge 6 structural prototype, or 166-kagome metals, have recently been proposed as a chemically flexible route for exploring the interplay between topology, correlations and magnetism [5,6,10,[20][21][22][23][24][25][26].…”

The role of electron correlations in the electronic structure of putative Chern magnet TbMn$_6$Sn$_6$ using correlated methods

“…Rare-earth (R) material class RMn 6 Sn 6 displays rich and intricate physical phenomena consisting of strong electron-electron correlations, spin-orbit effects, and supposedly topological behavior [1][2][3][4][5][6][7][8][9][10]. These materials belong to the P 6/mmm (#191) space group, where Mn atoms form 2D kagome layers interlaced with R and Sn layers, see Figure 1.…”

Evolution of the Chern Gap in Kagome Magnet HoMn6Sn6−xGex

“…Thusly, the Kagome system is one of the most tunable condensed matter systems explored in recent times. Although this system has many candidates for the discovery of new properties, there is a large interest in RMn 6 Sn 6 (R = rare earth elements) [36,37], which can be easily grown with the in-flux technique.…”