Structure, magnetic ordering, and Kondo effect in(Ce1−xNdx)3Al

Abstract

A systematic study for ${({\text{Ce}}_{1\ensuremath{-}x}{\text{Nd}}_{x})}_{3}\text{Al}$ $(x=0--1.0)$ compounds has been performed by measuring lattice parameters, electrical resistivity, magnetization, and specific heat. All samples exhibit the hexagonal crystal structure at room temperature. The lattice parameters and unit-cell volume decrease monotonically with increasing Nd content $(x)$. An obvious hysteresis in temperature dependence of resistivity, which was attributed to the crystal structural phase transition, is found at $x\ensuremath{\le}0.3$. The low-temperature resistivity shows $\text{log}\text{ }T$ dependence, suggesting the Kondo effect at $x\ensuremath{\le}0.3$. The N\'eel temperature and structural transition temperature $({T}_{S})$ decrease with increasing $x$, ${T}_{S}$ merges with the antiferromagnetic (AFM) transition, and the Curie temperature increases linearly with increasing $x$ at $x\ensuremath{\ge}0.2$. Thus $x\ensuremath{\sim}0.2$ is a critical point where the ferromagnetic order and Kondo effect compete at low temperature. The effective magnetic moments ${\ensuremath{\mu}}_{eff}$ almost linearly decrease with increasing $x$ and agree with the estimation assuming ${\text{Nd}}^{3+}$ and ${\text{Ce}}^{3+}$ states, indicating that the change in the electronic structures of Nd and Ce ions in the ground states is very small in the entire range. The characteristic temperature ${T}_{0}$ which was obtained by the fitting of Rajan's curve decreases with increasing $x$ at $x\ensuremath{\le}0.15$, i.e., a small fraction of Nd content strongly dilute the Kondo effect as well as AFM order.