Unconventional spin excitations in the S= 32 triangular antiferromagnet RbAg₂Cr[VO₄]₂

authored by

S. Lee, R. Klauer, J. Menten, W. Lee, S. Yoon, H. Luetkens, P. Lemmens, A. Möller, K. Y. Choi

Abstract

We present muon spin relaxation (μSR) measurements of the S=3/2 undistorted triangular lattice established in RbAg₂Cr[VO₄]₂. The zero-(ZF) and longitudinal-field μSR spectra evidence the absence of spin freezing and long-range magnetic ordering down to T=25 mK, supporting the formation of a dynamic ground state. Noticeably, we observe an anomalous temperature dependence of the ZF muon spin relaxation rate λZF(T), featuring a decrease below T=20 K. This suggests the alteration of the dominant relaxation mechanism by the development of short-range magnetic correlations. A subsequent leveling off of λZF(T) below T=2 K indicates persistent spin dynamics and reveals the presence of exotic magnetic excitations. The field dependence of the muon spin relaxation rate at T=25 mK is well described by a diffusive spin transport model with algebraic spin-spin correlations. The suppressed long-range order and the peculiar temperature-dependent behavior of λZF(T) will be discussed in terms of the exchange interaction between Cr³⁺ moments via nonmagnetic [VO₄]^3- entities. In the title compound, the degeneracy of the t2g-orbital set is not lifted by a space group symmetry reduction or subject to significant anisotropy resulting from spin-orbit coupling.

External Organisation(s)

Chung-Ang University
Rutherford Appleton Laboratory
Johannes Gutenberg University Mainz
Paul Scherrer Institut (PSI)
Technische Universität Braunschweig

Type

Article

Journal

Physical Review B

Volume

101

ISSN

2469-9950

Publication date

01.06.2020

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Condensed Matter Physics

Electronic version(s)

https://doi.org/10.1103/PhysRevB.101.224420 (Access: Unknown)