Seminars at the Landau Institute scientific council
Seminars are held on Fridays in the conference hall of Landau Institute for Theoretical Physics in Chernogolovka, beginning at 11:30.
Effective mass and field-reinforced superconductivity in uranium compounds
15 March in 11:30
A theory of strong coupling superconductivity in uranium compounds has been developed, based on electron-electron interaction through magnetic fluctuations described by frequency-dependent magnetic susceptibility. The magnetic field dependence of the electron effective mass is expressed through the field dependence of the magnetic susceptibility components. It is shown that the intensity of triplet pairing, and hence the critical temperature of the transition to the superconducting state, is also determined by the field-dependent susceptibility. The results are discussed in relation to the properties of ferromagnetic uranium compounds URhGe and UCoGe, as well as the recently discovered UTe2.
Current induced magnetisation in metal without space-inversion symmetry
15 March in 11:30
Magneto-electric effect, that is an appearance of magnetisation induced by electric current is allowed by symmetry in metals with crystal structure without space inversion. The microscopic origin of this effect is spin-orbit coupling of electrons with a non-centrosymmetric crystal lattice lifting spin degeneracy of electron energy and mixing spin and orbital degrees of freedom. The presented calculation of magnetisation induced by current based on the application of kinetic equation for the matrix distribution function of electrons occupying the states in two bands split by the spin-orbit interaction.
Andreev conductance in disordered SF junctions with spin-orbit scattering
22 March in 11:30
M.E. Ismagambetov, P.M. Ostrovsky and M.V. Feigel’man
We present an idea of a new method to measure spin-orbit scattering rate in strongly disordered superconducting materials. The method is based upon specific Andreev reflection phenomenon at the boundary between superconductor and half-metal (fully polarized metallic ferromagnet). We demonstrate theoretically that spin-orbit scattering leads to a formation of a fluctuating in space triplet component of superconducting order parameter ∆_p(r) with zero average. However, Andreev conduction to half-metal is allowed due to mesoscopic fluctuations of this order parameter. The effect is expected to be strong in superconducting materials like amorphous InOx and others with not very large values of kF l product.