1,204 research outputs found
Tunnelling between non-centrosymmetric superconductors with significant spin-orbit splitting studied theoretically within a two-band treatment
Tunnelling between non-centrosymmetric superconductors with significant
spin-orbit splitting is studied theoretically in a two-band treatment of the
problem. We find that the critical Josephson current may be modulated by
changing the relative angle between the vectors describing absence of inversion
symmetry on each side of the junction. The presence of two gaps also results in
multiple steps in the quasiparticle current-voltage characteristics. We argue
that both these effects may help to determine the pairing states in materials
like CePtSi, UIr and CdReO. We propose experimental tests of
these ideas, including scanning tunnelling microscopy.Comment: 5 pages, 1 figure. Minor changes. Some new references added.
Journal-ref. adde
NMR relaxation rate in non-centrosymmetric superconductors
The spin-lattice relaxation rate of nuclear magnetic resonance in a clean
superconductor without inversion center is calculated for arbitrary pairing
symmetry and band structure, in the presence of strong spin-orbit coupling.Comment: 4 page
Signature of superconducting states in cubic crystal without inversion symmetry
The effects of absence of inversion symmetry on superconducting states are
investigated theoretically. In particular we focus on the noncentrosymmetric
compounds which have the cubic symmetry like LiPtB. An appropriate
and isotropic spin-orbital interaction is added in the Hamiltonian and it acts
like a magnetic monopole in the momentum space. The consequent pairing
wavefunction has an additional triplet component in the pseudospin space, and a
Zeeman magnetic field can induce a collinear supercurrent
with a coefficient . The effects of anisotropy embedded in the cubic
symmetry and the nodal superconducting gap function on are also
considered. From the macroscopic perspectives, the pair of mutually induced
and magnetization can affect the distribution of magnetic
field in such noncentrosymmetric superconductors, which is studied through
solving the Maxwell equation in the Meissner geometry as well as the case of a
single vortex line. In both cases, magnetic fields perpendicular to the
external ones emerge as a signature of the broken symmetry.Comment: 16 pages in pre-print forma
Topological Order and Non-Abelian Statistics in Noncentrosymmetric s-Wave Superconductors
We demonstrate that in two-dimensional noncentrosymmetric s-wave
superconductors under applied magnetic fields for a particular electron
density, topological order emerges, and there exists a zero energy Majorana
fermion mode in a vortex core, which obeys non-Abelian statistics, in analogy
with p_x+ip_y superconductors, the Moore-Read Pfaffian quantum Hall state, and
the gapped non-Abelian spin liquid phase of the Kitaev model.Comment: 4 pages, 2 figure
Helical vortex phase in the non-centrosymmetric CePt_3Si
We consider the role of magnetic fields on the broken inversion
superconductor CePt_3Si. We show that upper critical field for a field along
the c-axis exhibits a much weaker paramagnetic effect than for a field applied
perpendicular to the c-axis. The in-plane paramagnetic effect is strongly
reduced by the appearance of helical structure in the order parameter. We find
that to get good agreement between theory and recent experimental measurements
of H_{c2}, this helical structure is required. We propose a Josephson junction
experiment that can be used to detect this helical order. In particular, we
predict that Josephson current will exhibit a magnetic interference pattern for
a magnetic field applied perpendicular to the junction normal. We also discuss
unusual magnetic effects associated with the helical order.Comment: 5 pages, 2 figures, Accepted as Phys Rev. Lette
Using Josephson junctions to determine the pairing state of superconductors without crystal inversion symmetry
Theoretical studies of a planar tunnel junction between two superconductors
with antisymmetric spin-orbit coupling are presented. The half-space Green's
function for such a superconductor is determined. This is then used to derive
expressions for the dissipative current and the Josephson current of the
junction. Numerical results are presented in the case of the Rashba spin-orbit
coupling, relevant to the much studied compound CePtSi. Current-voltage
diagrams, differential conductance and the critical Josephson current are
presented for different crystallographic orientations and different weights of
singlet and triplet components of the pairing state. The main conclusion is
that Josephson junctions with different crystallographic orientations may
provide a direct connection between unconventional pairing in superconductors
of this kind and the absence of inversion symmetry in the crystal.Comment: 16 pages, 10 figure
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