Muon-spin relaxation study of the double perovskite insulators Sr$_{2}B$OsO$_6$ ($B={\rm Fe, Y, In}$)

TL;DR

This study uses muon-spin relaxation to investigate magnetic ordering in double perovskite insulators Sr$_{2}B$OsO$_6$ ($B={ m Fe, Y, In}$), revealing phase transitions and magnetic structures through experimental and computational methods.

Contribution

It provides the first muon-spin relaxation analysis of these specific double perovskite insulators, identifying magnetic phases and candidate muon sites with combined experimental and density functional calculations.

Findings

Long-range magnetic order in Sr$_{2}$FeOsO$_6$ below 135 K.

Coexistence of AF1 and AF2 phases below 67 K causes loss of oscillations.

Identification of muon stopping sites consistent with magnetic structures.

Abstract

We present the results of zero-field muon-spin relaxation measurements made on the double perovskite insulators Sr$_{2}B$OsO$_6$ ($B={\rm Fe, Y, In}$). Spontaneous muon-spin precession indicative of quasistatic long range magnetic ordering is observed in Sr$_{2}$FeOsO$_6$ within the AF1 antiferromagnetic phase for temperatures below $T_{\rm N}=135 \pm 2~{\rm K}$. Upon cooling below $T_2 \approx 67~{\rm K}$ the oscillations cease to be resolvable owing to the coexistence of the AF1 and AF2 phases, which leads to a broader range of internal magnetic fields. Using density functional calculations we identify a candidate muon stopping site within the unit cell, which dipole field simulations show to be consistent with the proposed magnetic structure. The possibility of incommensurate magnetic ordering is discussed for temperatures below $T_{\rm N}=53~{\rm K}$ and 25~K for Sr$_{2}$YOsO$_6$ and Sr$_{2}$InOsO$_6$, respectively.