Random magnetic moments and spin-glass-like behaviors in the heavy-fermion compoundCeNi2Sn2

Abstract

We have studied the magnetic, electric, and thermal properties of ${\mathrm{CeNi}}_{2}{\mathrm{Sn}}_{2}.$ The zero-field-cooled susceptibility ${\ensuremath{\chi}}_{\mathrm{ZFC}}(T)$ deviates from the field-cooled susceptibility ${\ensuremath{\chi}}_{\mathrm{FC}}(T)$ below 3 K. Both real $({\ensuremath{\chi}}^{\ensuremath{'}})$ and imaginary $({\ensuremath{\chi}}^{\ensuremath{''}})$ components of the ac susceptibility exhibit pronounced maxima at \ensuremath{\sim}4 and \ensuremath{\sim}5 K. At 2 K, the magnetization $M(H)$ clearly exhibits hysteresis. The zero-field cooled-magnetization ${M}_{\mathrm{ZFC}}(t)$ is frozen at 2 K in a 0.005-T field with an enormous time constant of 917 sec. In 0.005 T, zero-field-cooled resistivity ${\ensuremath{\rho}}_{\mathrm{ZFC}}(T)$ starts to deviate from field-cooled resistivity ${\ensuremath{\rho}}_{\mathrm{FC}}(T)$ at \ensuremath{\sim}8 K, and both ${\ensuremath{\rho}}_{\mathrm{ZFC}}(T)$ and ${\ensuremath{\rho}}_{\mathrm{FC}}(T)$ rapidly decrease as the temperature is below 5 K. These behaviors suggest a spin-glass phase transition at ${T}_{f}\ensuremath{\sim}3\mathrm{K}$ for ${\mathrm{CeNi}}_{2}{\mathrm{Sn}}_{2}.$ The coefficient of the term linear in temperature \ensuremath{\gamma}, in the specific heat of ${\mathrm{CeNi}}_{2}{\mathrm{Sn}}_{2}$ between 30 and 40 K, is 112 mJ ${\mathrm{mol}}^{\mathrm{\ensuremath{-}}1}$ ${\mathrm{K}}^{\mathrm{\ensuremath{-}}2}$, which is much larger than those of normal metals. ${\mathrm{CeNi}}_{2}{\mathrm{Sn}}_{2}$ is a true heavy fermion with spin-glass-like behavior. In a 10-T field, the temperature dependence of ${C}_{m}/T$ exhibits a peak at \ensuremath{\sim}5 K. The easiest interpretation for this behavior is that, in a high magnetic field, there is a field-induced ferromagnetic phase transition at \ensuremath{\sim}5 K.