Magnetic Anisotropy of SrCu$_2$(BO$_3$)$_2$ System as Revealed by X-Band ESR

TL;DR

This study uses X-band ESR measurements on SrCu$_2$(BO$_3$)$_2$ to investigate its magnetic anisotropy, revealing the significance of Dzyaloshinsky-Moriya interactions and spin-phonon coupling effects.

Contribution

It introduces a generalized model including intradimer DM interactions and highlights the role of spin-phonon coupling in linewidth broadening.

Findings

Broad ESR absorption lines indicate large anisotropy from DM interactions.

Generalized model includes intradimer Dzyaloshinsky-Moriya terms.

Spin-phonon coupling causes linewidth broadening with temperature.

Abstract

X-band ESR measurements on a single crystal of the highly frustrated SrCu$_2$(BO$_3$)$_2$ system are shown to provide an essential inspection of the magnetic anisotropy present in this compound. The very broad absorption lines seem to be consistent with the largest anisotropy term, namely, the antisymmetric Dzyaloshinsky-Moriya (DM) interaction allowed by symmetry. However, the previously well-accepted model of only interdimer interaction is generalized with additional intradimer DM terms. Moreover, spin-phonon coupling is recognized as the cause on the linewidth broadening with increasing temperature.