Influence of a Strong Magnetic Field on the Tetragonal Phase ofV3Si-Type Compounds

The effects of a strong magnetic field ($H>\mathrm{}{H}_{c2\mathrm{}}$) on the tetragonal phase of ${\mathrm{V}}_3$Si are studied theoretically using the Labbé-Friedel model. Starting from the free-energy expression for the system, we have calculated the spontaneous strain ${\epsilon }_0$, the $d$-electron spin magnetization $M$, and the Pauli-spin susceptibility $\chi$ as functions of field strength $H$ at both $T=0\mathrm{}$ °K and $T\ne 0$ °K. The structural transition temperature as a function of magnetic field is also obtained. One essential feature of our results is that at any temperature below 17.4 °K some applied field $H_0$ will produce a discontinuous structural transformation from the state with $\frac{c}{a}>1\mathrm{}$ to that with $\frac{c}{a}<1\mathrm{}$. At $T=0\mathrm{}$ °K, $H_0=298\mathrm{}$ kOe; at $T=17.4\mathrm{}$ °K, $H_0=275\mathrm{}$ kOe.