Anisotropic magnetic phase diagrams, tricriticality, and spin-reorientation in high-pressure grown SmCrO$_3$ single crystals

TL;DR

This study reports the successful growth of high-quality SmCrO$_3$ single crystals and investigates their complex magnetic phase diagrams, revealing a discontinuous spin-reorientation and tricritical behavior influenced by anisotropic magnetic interactions.

Contribution

First detailed investigation of SmCrO$_3$ single crystal magnetic phase diagrams, revealing new spin-reorientation behavior and clarifying complex magnetic interactions.

Findings

Discontinuous spin-reorientation at 33 K in single crystals

Tricritical point observed for magnetic field along the a axis

Magnetic structure consistent with representation $ ext{Gamma}_4$ above $T_{SR}$

Abstract

SmCrO$_3$ single crystals were successfully grown utilizing the high-pressure optical floating-zone method and their crystal structure, magnetization behavior, and magnetic phase diagrams were thoroughly investigated. Magnetic studies were conducted for fields applied along all principal crystallographic directions, with measurements taken at temperatures as low as 0.4 K and magnetic fields up to 14 T. The single crystal growth parameters are reported and the orthorhombic structure with the centrosymmetric space group $Pbnm$ is confirmed. Long-range order of the Cr$^{3+}$ and Sm$^{3+}$ magnetic sublattices evolves at $T_{\rm N}$ = 192 K and $T_{\rm N2}$=3 K, respectively. In contrast to previous studies on polycrystals our single crystal data imply a discontinuous and one-step spin-reorientation (SR) of net magnetic moments $\tilde{M}$ from the $c$ axis into the $ab$ plane at zero magnetic field at $T_{\rm SR}$=33 K. Its discontinuous nature is maintained if $B$ is applied $||c$ axis but tricritical behavior and a triple point is found for $B||a$ axis. While our data are consistent with the magnetic representation $\Gamma_4$ for $T > T_{\mathrm {SR}}$, the size and in-plane direction of the observed net magnetic moment disagree to previously proposed spin configurations, i.e., $\Gamma_1$ and $\Gamma_2$, for the spin-reoriented phases. In general, our high-quality single crystals enable us to revisit the phase diagram and to clarify the complex magnetism in SmCrO3 arising from the interplay of anisotropic 3$d$ and 4$f$ magnetic sublattices.