5 research outputs found
Paramagnetic limit of superconductivity in a crystal without inversion center
The theory of paramagnetic limit of superconductivity in metals without
inversion center is developed. There is in general the paramagnetic suppression
of superconducting state. The effect is strongly dependent on field orientation
in respect to crystal axes. The reason for this is that the degeneracy of
electronic states with opposite momenta forming of Cooper pairs is lifted by
magnetic field but for some field directions this lifting can be small or even
absent.Comment: 9 pages, no figure
S-wave/spin-triplet order in superconductors without inversion symmetry: LiPdB and LiPtB
We investigate the order parameter of noncentrosymmetric superconductors
LiPdB and LiPtB via the behavior of the penetration depth
. The low-temperature penetration depth shows BCS-like behavior in
LiPdB, while in LiPtB it follows a linear temperature
dependence. We propose that broken inversion symmetry and the accompanying
antisymmetric spin-orbit coupling, which admix spin-singlet and spin-triplet
pairing, are responsible for this behavior. The triplet contribution is weak in
LiPdB, leading to a wholly open but anisotropic gap. The significantly
larger spin-orbit coupling in LiPtB allows the spin-triplet component
to be larger in LiPtB, producing line nodes in the energy gap as
evidenced by the linear temperature dependence of . The
experimental data are in quantitative agreement with theory.Comment: Phys. Rev. Lett. (in press). More details are include
Possible nodeless superconductivity in the noncentrosymmetric superconductor Mg_(12-delta)Ir_19B_16
We measured the resistivity, diamagnetization, and low-temperature specific
heat of the newly discovered noncentrosymmetric superconductor
Mg_(12-delta)Ir_19B_16. The temperature dependence of specific heat is
consistent with the model of an isotropic s-wave gap with value Delta_0 = 0.94
meV for the sample Tc = 5.7 K, and the ratio Delta_0/k_BTc = 1.91 indicates a
slightly moderate coupling for the superconductivity. The correlations among
the normal state Sommerfeld constant gamma_n, the slope -dHc2(T)/dT near Tc,
and the condensation energy Ec are all consistent with the slightly moderate
coupling picture. Based on the data of phonon contribution, Tc and the McMillan
formula, we obtained an electron-phonon coupling strength lambda_(e-ph) = 0.66,
which suggests that the superconductivity here is induced by the
electron-phonon coupling.Comment: 6 pages, 7 figure
Magnetoelectric effect and the upper critical field in superconductors without inversion center
Solving the Ginzburg–Landau equation we demonstrate that the paramagnetic limiting of superconducting state in the superconductors without space inversion symmetry is significantly weakened. It is caused by so called magnetoelectric mechanism proving to be effective or not depending of the magnetic field direction and the crystal symmetry