Magnetic Field Induced Gap and Kink Behavior of Thermal Conductivity

The thermal conductivity of a quasiparticle (QP) system described by a relativistic four-fermion interaction model in the presence of an external magnetic field is calculated. It is shown that, for narrow width of quasiparticles, the thermal conductivity, as a function of the applied magnetic field, exhibits a kink behavior at a critical field $B_{c}\sim T^{2}$. The kink is due to the opening of a gap in the QP spectrum at a critical magnetic field $B_c$ and to the enhancement of the transitions between the zeroth and first Landau levels. Possible applications of the results are discussed.