Coexistence of Ferromagnetism with Spin Triplet Superconductivity |
| G. Górski, K. Kucab and J. Mizia
Institute of Physics, Rzeszów University, al. Rejtana 16A, 35-959 Rzeszów, Poland |
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| The experimental results for ZrZn2, URhGe, and in some pressure ranges also for UGe2, showed that the ferromagnetic superconductors are weak itinerant ferromagnets. Guided by these results we describe the phenomenon of coexistence between equal spin triplet pairing superconductivity and ferromagnetism using the extended Stoner model, which includes in Hamiltonian the on-site Coulomb interaction, U, and occupation dependent hopping integral. We use the Hartree-Fock approximation and the Green functions technique. In the Hartree-Fock approximation the on-site Coulomb interaction plays the role of the on-site exchange (Hund's) field. All inter-site interactions will have included the inter-site kinetic correlation, 〈 ciσ+cjσ 〉, within the Hartree-Fock approximation. We introduce the pressure-dependence to the hopping integral. Numerical results are compared with experimental data for ZrZn2. The kinetic correlation creates the superconductivity without help of negative values of the Coulomb interactions. The model can explain stimulation of triplet superconductivity by the weak itinerant ferromagnetism. This effect was observed experimentally in ZrZn2. Numerical analysis also confirms the experimental effect of decrease in critical temperatures (Curie and superconducting) with increasing external pressure. |
| DOI: 10.12693/APhysPolA.115.141 PACS numbers: 71.10.Fd, 74.20.-z, 75.10.Lp |