Phase diagram for an antiferromagnet with the prevailing Dzyaloshinski interaction

A phase diagram is constructed in variable H2, Hy for an easy-axis tetragonal antiferromagnet with the prevailing Dzyaloshinski interaction. In this diagram the lines of second order transitions between an angular phase and phase, in which the vector of antiferromagnetic 1 is perpendicular to the easy magnetic axis (EMA), begin and in the spin-flip transition fields (i.e. in the exchange field). A peculiarity of these lines is that each of the lines has two tricritical points at which there occurs a transition to a first-order phase transition line. A critical angle between the magnetic field direction and the basal plane, within which the first-order phase transition occurs is determined. The position of the tricritical point in the phase Hz-Hy (or Hz-Hx) diagram also depends on temperature