Effect of random disorder and spin frustration on the reentrant spin glass phase and ferromagnetic phase in stage-2 Cu_{0.93}Co_{0.07}Cl_{2} graphite intercalation compound near the multicritical point

TL;DR

This study investigates how random disorder and spin frustration influence the magnetic phases and critical behavior of a stage-2 Cu-Co chloride graphite intercalation compound near a multicritical point, revealing complex phase transitions and critical exponents.

Contribution

It provides new insights into the magnetic phase transitions and critical phenomena in a reentrant ferromagnet with disorder and frustration near the multicritical point.

Findings

Identification of two magnetic phase transitions at T_RSG and T_c.

Observation of characteristic memory phenomena at transition temperatures.

Determination of critical slowing down with specific critical exponents.

Abstract

Stage-2 Cu$_{0.93}$Co$_{0.07}$Cl$_{2}$ graphite intercalation compound magnetically behaves like a reentrant ferromagnet near the multicritical point ($c_{MCP} \approx 0.96$). It undergoes two magnetic phase transitions at $T_{RSG}$ ($= 6.64 \pm 0.05$ K) and $T_{c}$ ($= 8.62 \pm 0.05$ K). The static and dynamic nature of the ferromagnetic and reentrant spin glass phase has been studied using DC and AC magnetic susceptibility. Characteristic memory phenomena of the DC susceptibility are observed at $T_{RSG}$ and $T_{c}$. The nonlinear AC susceptibility $\chi_{3}^{\prime}$ has a positive local maximum at $T_{RSG}$, and a negative local minimum at $T_{c}$. The relaxation time $\tau$ between $T_{RSG}$ and $T_{c}$ shows a critical slowing down: $\tau$ with $x = 13.1 \pm 0.4$ and $\tau_{0}^{*} = (2.5 \pm 0.5) \times 10^{-13}$ sec. The influence of the random disorder on the critical behavior above $T_{c}$ is clearly observed: $\alpha = -0.66$, $\beta = 0.63$, and $\gamma = 1.40$. The exponent of $\alpha$ is far from that of 3D Heisenberg model.