Spin-glass freezing in Kondo-lattice compounds in the presence of a random and a transverse magnetic field

Abstract

The present work studies the effects of a random magnetic field on the competition among Kondo effect, spin glass (SG) phase and ferromagnetic (FE) order in disordered cerium systems such as CeNi1−xCux. A Kondo lattice model is used with an intersite disordered interaction Jij between localized Ising spins in the presence of a transverse magnetic field Γ and a longitudinal random magnetic field. The disorders introduced by Jij and the random field follow Gaussian distributions. They are treated within the one-step replica symmetry breaking procedure. The results suggest that the presence of a random field affects strongly the FE and SG phases. It can disrupt the FE order completely and reduces the SG phase region. It can also introduce an independent spin phase that can coexist within the Kondo regime at high Kondo interaction Jk. On the other hand, the Γ field introduces quantum spin fluctuations able to destroy the magnetic order by decreasing the critical temperature towards a quantum critical point. In addition, the Kondo states can only occur at higher Jk values as Γ increases.