Magnetic phase diagram of Ca_1-xMn_xO

TL;DR

This study maps the magnetic phase diagram of Ca$_{1-x}$Mn$_x$O, revealing how magnetic order evolves with Mn content, transitioning from spin-glass to antiferromagnetic states, with different transition orders.

Contribution

It provides the first detailed magnetic phase diagram of Ca$_{1-x}$Mn$_x$O, identifying the nature of magnetic transitions across various Mn concentrations.

Findings

Magnetic order shifts from spin-glass to antiferromagnetic with increasing Mn.

Transitions are second order for 0.5 ≤ x ≤ 0.65 and first order for x ≥ 0.7.

High-temperature susceptibility fits a diluted Heisenberg magnet model.

Abstract

Alternating current susceptibility and direct current magnetization have been studied for polycrystalline Ca$_{1-x}$Mn$_x$O. On increasing the Mn content, magnetic ordering changes from spin-glass behavior for $0.25 \leqslant x \leqslant 0.4$ to antiferromagnetic order. The paramagnetic/antiferromagnetic transition is of second order for $0.5 \leqslant x \leqslant 0.65$ and of first order for $x \geqslant 0.7$. For low Mn concentrations, the high-temperature alternating current susceptibility can be described by a diluted Heisenberg magnet model developed for diluted magnetic semiconductors.