Field-induced phase transitions in a Kondo insulator

Abstract

We study the magnetic-field effect on a Kondo insulator by exploiting the periodic Anderson model with the Zeeman term. The analysis using dynamical mean field theory combined with quantum Monte Carlo simulations determines the detailed phase diagram at finite temperatures. At low temperatures, the magnetic field drives the Kondo insulator to a transverse antiferromagnetic phase, which further enters a polarized metallic phase at higher fields. The antiferromagnetic transition temperature $T_c$ takes a maximum when the Zeeman energy is nearly equal to the quasi-particle gap. In the paramagnetic phase above $T_c$, we find that the electron mass gets largest around the field where the quasi-particle gap is closed. It is also shown that the induced moment of conduction electrons changes its direction from antiparallel to parallel to the field.Comment: 7 pages, 6 figure

Mean-field study of the heavy-fermion metamagnetic transition

“…Such a contribution is necessary to reproduce the observed diamagnetism of the c electrons, which initially cant away from the applied field. 26,27 Summing the contributions of Eqs. (5) and (6) yields a complete mean field Hamiltonian,…”

“…A more common assumption is to set the two g-factors equal. 24,25,26,27 This choice, however, is a somewhat artificial limit 28 and, at the mean field level, leads to a nongeneric (g c = g f is a special tuning) magnetization plateau of width equal to the zero-field Kondo energy. 9,12 We do not attempt to model the anisotropy of g (it is in principle a tensor 29 ) by introducing explicit crystal field terms into the Hamiltonian.…”

High-field suppression of in-gap states in the Kondo insulatorSmB6

“…Antiferromagnetism in Kondo insulators with bipartite lattices has previously been predicted 28 and models of field-induced transitions to a metallic phase have been considered. 29 Although these models provide explanations for various Kondo phenomena, the nature of the in-gap states in SmB 6 remains unclear.…”

Superfluid State in the Periodic Anderson Model with Attractive Interactions

“…At this point, a field-induced magnetic phase transition occurs, where a spontaneous staggered magnetization appears in the plane perpendicular to the applied field. [34][35][36] In the PAM with attractive interactions, a similar competition is expected at low temperatures. The corresponding ordered phase should be characterized by a pair potential Á, which is given by…”