Abstract:
A study is made of the influence of an external magnetic field $H_0$ on the thermodynamic
properties of strongly anisotropic systems in the phase of coexistence of superconductivity
and a spin density wave. The basic equations are obtained for the order parameters of
these states, the difference between the free energies of the superconducting and normal
phases is calculated and the behavior of the system in a number of limiting cases is
investigated. The jump in the specific heat at the point $T=T_c$ is also calculated and
its dependence on the magnetic field $H_0$ investigated. It is shown that the values of the
thermodynamic characteristics of the system depend on the ratio of the densities $N_1$ and
$N_2$ of the electron states corresponding to different regions of the anisotropic Fermi
surface, and that the values are very different from the results of the BCS model.