Isotropic and Anisotropic Regimes of the Field-Dependent Spin Dynamics in Sr₂IrO₄: Raman Scattering Studies

Authors

Y. Gim, University of Illinois at Urbana-Champaign
A. Sethi, University of Illinois at Urbana-Champaign
Q. Zhao, Argonne National Laboratory
J. F. Mitchell, Argonne National Laboratory
Gang Cao, University of KentuckyFollow
S. L. Cooper, University of Illinois at Urbana-Champaign

Abstract

A major focus of experimental interest in Sr₂IrO₄ has been to clarify how the magnetic excitations of this strongly spin-orbit coupled system differ from the predictions of an isotropic 2D spin-1/2 Heisenberg model and to explore the extent to which strong spin-orbit coupling affects the magnetic properties of iridates. Here, we present a high-resolution inelastic light (Raman) scattering study of the low-energy magnetic excitation spectrum of Sr₂IrO₄ and Eu-doped Sr₂IrO₄ as functions of both temperature and applied magnetic field. We show that the high-field (H > 1.5 T) in-plane spin dynamics of Sr₂IrO₄ are isotropic and governed by the interplay between the applied field and the small in-plane ferromagnetic spin components induced by the Dzyaloshinskii-Moriya interaction. However, the spin dynamics of Sr₂IrO₄ at lower fields (H < 1.5 T) exhibit important effects associated with interlayer coupling and in-plane anisotropy, including a spin-flop transition at H_c in Sr₂IrO₄ that occurs either discontinuously or via a continuous rotation of the spins, depending on the in-plane orientation of the applied field. These results show that in-plane anisotropy and interlayer coupling effects play important roles in the low-field magnetic and dynamical properties of Sr₂IrO₄.

Document Type

Article

Publication Date

1-11-2016

Notes/Citation Information

Published in Physical Review B, v. 93, issue 2, 024405, p. 1-7.

©2016 American Physical Society

The copyright holder has granted permission for posting the article here.

Digital Object Identifier (DOI)

https://doi.org/10.1103/PhysRevB.93.024405

Funding Information

Research was supported by the National Science Foundation under Grant No. NSF DMR 14-64090. Work at the University of Kentucky was supported by the National Science Foundation via Grant No. NSF DMR 12-65162. Work at Argonne National Laboratory (crystal growth and magnetic characterization) was supported by the US Department of Energy Office of Science, Basic Energy Sciences, Materials Science and Engineering Division.

Repository Citation

Gim, Y.; Sethi, A.; Zhao, Q.; Mitchell, J. F.; Cao, Gang; and Cooper, S. L., "Isotropic and Anisotropic Regimes of the Field-Dependent Spin Dynamics in Sr₂IrO₄: Raman Scattering Studies" (2016). Physics and Astronomy Faculty Publications. 436.
https://uknowledge.uky.edu/physastron_facpub/436