Effective interaction between localized magnetic moments in ferromagnetic superconductors is studied microscopically by taking account of the interplay among the electromagnetic field, persistent current and magnetic moments. The obtained effective exchange coupling Jij(q) can stabilize the spin-spiral ordering with a finite wave number Q, which coexists with superconductivity. By using this Jij(q), the spin wave spectrum ħωq in the spin-spiral state is calculated at zero temperature. Reflecting a characteristic anisotropy of Jji(q), ħωq depends strongly on the direction of q; for q⁄⁄Q it has a prominent peak at q∼Q, but the peak vanishes as q deviates from the Q direction. It is also shown that ħωq has many energy gaps characteristic of the magnetic superconductor.
ASJC Scopus subject areas
- Physics and Astronomy(all)