Structural and magnetic properties of the 5$d^2$ double perovskites Sr$_2 B$ReO$_6$ ($B$ $=$ Y, In)

TL;DR

This study investigates the magnetic ground states of 5d^2 double perovskites Sr2YReO6 and Sr2InReO6 using various experimental techniques, revealing spin glass and non-magnetic singlet states influenced by spin-orbit coupling and crystal fields.

Contribution

It provides detailed experimental insights into the magnetic properties of these double perovskites and highlights the interplay of spin-orbit coupling, crystal fields, and exchange interactions as key factors.

Findings

Sr2YReO6 is a spin glass.

Sr2InReO6 hosts a non-magnetic singlet state.

Magnetic ground states vary due to competing interactions.

Abstract

We have performed magnetic susceptibility, heat capacity, neutron powder diffraction, and muon spin relaxation experiments to investigate the magnetic ground states of the 5$d^2$ double perovskites Sr$_2$YReO$_6$ and Sr$_2$InReO$_6$. We find that Sr$_2$YReO$_6$ is a spin glass, while Sr$_2$InReO$_6$ hosts a non-magnetic singlet state. By making detailed comparisons with other 5$d^2$ double perovskites, we argue that a delicate interplay between spin-orbit coupling, non-cubic crystal fields, and exchange interactions plays a key role in the great variation of magnetic ground states observed for this family of materials.