Magnetic Phase Diagram of a Random Mixture with Competing Interactions: Co_1-<i>x</i>Mn<i>x</i>Cl₂·2H₂O

Abstract

Magnetic and thermal properties of Co 1- x Mn x Cl 2 ·2H 2 O with competing exchange interactions have been studied experimentally, For the system with x ∼0.5, the magnetic heat capacity have revealed only a broad maximum around 5 K, which is quite different from the heat capacity peak of λ-type for the pure systems and similar to that observed in metallic spin-glasses. The hysteresis in the magnetic susceptibility and thermoremanent magnetization have been observed in the mixtures with x ≤0.5, reflecting the frustration of magnetic interactions, while normal antiferromagnetic behavior has been seen in the region x >0.5. The magnetic phase diagram of this system is given, which contains four states: paramagnetic, antiferromagnetic, frustrated antiferromagnetic and anisotropic spin-glass states.