Calculation of magnetic dipole fields on M+-meson in ferromagnets

The magnetic dipole field at a μ+-meson in iron, nickel and cobalt is calculated. The crystallographic structure of the ferromagnets is taken into account. The case of a diffusing μ+-meson is considered. The magnetic field (Bq'' vector) at the μ+-meson i.e. in the centre of the pore, was calculated with the formula Bq''=Σsub(i=1,n)(3(m.rsub(i))rsub(i)/(rsub(i).rsub(i))sup(5/2) - m/(rsub(i).rsub(i)) sup(3/2)) (Bq'', rsub(i), m, vectors). Here vector rsub(i) is the distance of the i-th lattice atom from the μ+-meson, vector m is the magnetic moment of the ferromagnetic atoms. The sum is taken over all atoms in the sphere rsub(i)<R, where R is the radius of the pore. The calculated field Bq'' in octa- and tetra-pores of nickel is zero for all directions of the magnetization. In the table the dependence of the dipole fields in homgeneously magnetized single crystals of iron and cobalt on the radius of the sphere is given. One sees from this that with increasing n (n is an integer connecting R with the lattice parameter) the field Bq'' at the μ+-meson reaches a definite limit value. In cobalt the field Bq'' is considerably lower than in iron. In a cobalt crystal the field Bq'', averaged over the octa- and tetra-pores, is zero and depends on the direction of the magnetization of the crystal