Ce2CuGe3:A nonmagnetic atom-disorder spin glass

Abstract

We have studied the magnetic, electric, and thermal properties of ${\mathrm{Ce}}_{2}{\mathrm{CuGe}}_{3}.$ The zero-field cooled susceptibility ${\ensuremath{\chi}}_{\mathrm{ZFC}}(T)$ deviates from the field-cooled susceptibility ${\ensuremath{\chi}}_{\mathrm{FC}}(T)$ below 3 K, which suggests a spin-glass phase transition at ${T}_{f}=3\mathrm{K}.$ The real $({\ensuremath{\chi}}^{\ensuremath{'}})$ and imaginary $({\ensuremath{\chi}}^{\ensuremath{''}})$ components of the ac susceptibility exhibit pronounced maxima at \ensuremath{\sim}3 K and \ensuremath{\sim}2 K, respectively. At 2 K, the magnetization $M(H)$ clearly exhibits hysteresis. Below 6 K, ${\mathrm{Ce}}_{2}{\mathrm{CuGe}}_{3}$ shows small spontaneous magnetic ordering. The specific heat $C(T)$ of ${\mathrm{Ce}}_{2}{\mathrm{CuGe}}_{3}$ presents a peak \ensuremath{\sim}4 K. Since the magnetic entropy between 2 and 4 K is much smaller than $2R\mathrm{ln}2,$ the 4-K peak of $C(T)$ is unlikely related to a long-range magnetic ordering. This 4-K peak of $C(T)$ might be due to Schottky anomaly with spin-glass contribution. The coefficient of the term linear in temperature in the specific heat \ensuremath{\gamma} of ${\mathrm{Ce}}_{2}{\mathrm{CuGe}}_{3}$ is 249.86 mJ ${\mathrm{mole}}^{\mathrm{\ensuremath{-}}1}$ ${\mathrm{K}}^{\mathrm{\ensuremath{-}}2}$, which is much larger than that of normal metals. A spin-glass magnetism could result in a possible enlargement of the specific heat. At 2 K, the resistance $R(H)$ features hysteresis. This compound might be classified as a nonmagnetic atom-disorder spin glass or a reentrant spin glass.