Enhanced magnetism and suppressed magnetoelastic coupling induced by electron doping in Ca$_{1-x}$Y$_{x}$MnReO$_6$

TL;DR

This study investigates how electron doping in Ca$_{1-x}$Y$_{x}$MnReO$_6$ enhances magnetic ordering and suppresses magnetoelastic coupling, revealing changes in magnetic properties and lattice behavior.

Contribution

It provides new insights into the effects of electron doping on magnetic and structural properties of Ca$_{1-x}$Y$_{x}$MnReO$_6$, including increased $T_c$ and altered magnetoelastic interactions.

Findings

Magnetic ordering temperature increases from 121 K to 150 K.

Electron doping enhances ferromagnetic component of Mn spins.

Doping suppresses lattice anomalies at $T_c$.

Abstract

The Ca$_2$MnReO$_6$ double perovskite is a spin-orbit-assisted Mott insulator with exotic magnetic properties, including a largely non-collinear Mn$^{2+}$ spin arrangement and nearly orthogonal coupling between such spins and the much smaller Re $5d$ magnetic moments. Here, the electron-doped compound Ca$_{1.7}$Y$_{0.3}$MnReO$_6$ is investigated. Neutron and X-ray powder diffraction confirm that nearly full chemical order is maintained at the Mn and Re sites under the Y substitution at the Ca site. X-ray absorption measurements and an analysis of the Mn-O/Re-O bond distances show that the Mn oxidation state remains stable at +2 whereas Re is reduced upon doping. The electron doping increases the magnetic ordering temperature from $T_c = 121$ to $150$ K and also enhances significantly the ferromagnetic component of the Mn spins at the expense of the antiferromagnetic component at the base temperature ($T=3$ K). The lattice parameter anomalies at $T_c$ observed in the parent compound are suppressed by the electron doping. The possible reasons for the enhanced magnetism and the suppressed magnetoelastic coupling in Ca$_{1.7}$Y$_{0.3}$MnReO$_6$ are discussed.