Compass Impurity Model of Tb Substitution in Sr2IrO4

Abstract

We show that upon Tb substitution the interaction between the magnetic moments on the impurity Tb${}^{4+}$ ion and its surrounding Ir${}^{4+}$ ions is described by a "compass" model, i.e., Ising-like interaction favoring the magnetic moments across each bond to align along the bond direction. Such interaction nucleates quenched magnetic vortices near the impurities and drives a reentrant transition out of the antiferromagnetic ordered phase at low temperatures hence quickly suppresses the Néel temperature consistent with the experiment [Phys. Rev. B \textbf{92}, 214411 (2015)]. As a by-product, we propose that the compass model can be realized in ordered double perovskites composed of the spin-orbital-coupled $d^5$ ions and the half-closed-shell $f^7$ ions.

5 pages, 3 figures. published version, only slightly revised

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Cited by in corpus (5)

• The Jeff=1/2 antiferromagnet Sr2IrO4: A golden avenue toward new physics and functions
• Pseudo-Goldstone modes and dynamical gap generation from order-by-thermal-disorder
• Ground state properties of the Heisenberg-compass model on the square lattice
• Exact Ground States and Phase Diagram of the Quantum Compass Model under an in-plane Field
• Phase diagram and Ashkin-Teller universality in the classical square-lattice Heisenberg-compass model