Orbital character of the spin-reorientation transition in TbMn6Sn6

S. X. M. Riberolles, Tyler J. Slade, R. L. Dally, P. M. Sarte, Bing Li, Tianxiong Han, H. Lane, C. Stock, H. Bhandari, N. J. Ghimire, D. L. Abernathy, P. C. Canfield, J. W. Lynn, B. G. Ueland, R. J. McQueeney*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Ferromagnetic (FM) order in a two-dimensional kagome layer is predicted to generate a topological Chern insulator without an applied magnetic field. The Chern gap is largest when spin moments point perpendicular to the kagome layer, enabling the capability to switch topological transport properties, such as the quantum anomalous Hall effect, by controlling the spin orientation. In TbMn6Sn6, the uniaxial magnetic anisotropy of the Tb3+ ion is effective at generating the Chern state within the FM Mn kagome layers while a spin-reorientation (SR) transition to easy-plane order above TSR = 310 K provides a mechanism for switching. Here, we use inelastic neutron scattering to provide key insights into the fundamental nature of the SR transition. The observation of two Tb excitations, which are split by the magnetic anisotropy energy, indicates an effective two-state orbital character for the Tb ion, with a uniaxial ground state and an isotropic excited state. The simultaneous observation of both modes below TSR confirms that orbital fluctuations are slow on magnetic and electronic time scales < ps and act as a spatially-random orbital alloy. A thermally-driven critical concentration of isotropic Tb ions triggers the SR transition.
Original languageEnglish
Article number2658
Pages (from-to)1-8
Number of pages8
JournalNature Communications
Volume14
Issue number1
DOIs
Publication statusPublished - 9 May 2023

Keywords / Materials (for Non-textual outputs)

  • cond-mat.str-el

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