Spin-orbit coupling controlled ground state in Sr$_2$ScOsO$_6$

TL;DR

This study reveals that spin-orbit coupling induces a significant spin gap in Sr2ScOsO6, influencing its magnetic ground state and emphasizing the importance of spin-orbit effects in 4d3 and 5d3 systems.

Contribution

It demonstrates that spin-orbit-induced anisotropy is crucial for the magnetic ground state in Sr2ScOsO6, highlighting physics beyond traditional coupling models.

Findings

Large spin gap observed via neutron scattering

Spin-orbit-induced anisotropy is essential for antiferromagnetic order

Modeling requires including exchange anisotropy in Heisenberg Hamiltonian

Abstract

We report neutron scattering experiments which reveal a large spin gap in the magnetic excitation spectrum of weakly-monoclinic double perovskite Sr2ScOsO6. The spin gap is demonstrative of appreciable spin-orbit-induced anisotropy, despite nominally orbitally-quenched 5d3 Os5+ ions. The system is successfully modeled including nearest neighbor interactions in a Heisenberg Hamiltonian with exchange anisotropy. We find that the presence of the spin-orbit-induced anisotropy is essential for the realization of the type I antiferromagnetic ground state. This demonstrates that physics beyond the LS or JJ coupling limits plays an active role in determining the collective properties of 4d3 and 5d3 systems, and that theoretical treatments must include spin-orbit coupling.