The susceptibility maximum of ZrZn2 at high pressure

The electronic structure of ZrZn2 is calculated by a self-consistent linear muffin-tin orbital method within the atomic sphere approximation. From fixed-spin-moment calculations the magnetic moment M is estimated as a function of magnetic field H. By fitting the calculated values of M(H) to the form H=aM+bM3+cM5+dM7+eM9, the coefficients a, b, c, d, e are estimated as functions of the lattice constant. It is shown that the values of a and b are negative and positive, respectively, at the observed lattice constant at ambient pressure. With decreasing lattice constant the value of a changes its sign from negative to positive, which means that the ferromagnetic state is unstable. At a lattice constant a little smaller than the critical one, the value of b also changes its sign from positive to negative. These results, together with the other coefficients c-e, indicate a broad maximum in the temperature dependence of the susceptibility when the effect of spin fluctuations is taken into account. However, the absolute value of b is so small that the metamagnetic transition does not occur. It is shown that the anomalous temperature dependence of the susceptibility of ZrZn2 observed recently at high pressure is well described by the present calculations. (author)