Condensed Matter Seminar
Spin-orbit assisted superconductivity in transition metal dichalcogenides
Prof. Maxim Khodas
Faculty of Mathematics and Sciences,HUJI
Abstract
Mono- and few-layer transition metal dichalcogenides (TMDs) are two-dimensional superconductors with the transition temperature of a few Kelvins.
These superconductors have an extremely anisotropic critical magnetic field with the parallel critical field far above the Pauli limit.
The mono-layer TMDs are non-centrosymmetric with strong spin-orbit interaction polarizing spins out-of-plane.
The spin-orbit interaction protects the conventional spin-singlet superconductivity against the pair breaking by the magnetic field.
We argue that in addition, the spin-orbit interaction mediates the transformation of singlet Cooper pairs into the triplet Cooper pairs by the applied field.
These parallel spin triplets are distinct from the anti-parallel spin triplets present at zero magnetic field.
Since the parallel spin triplets are field induced, they have a strong effect on the critical field.
Besides, these spin triplets are protected against the disorder scattering thanks to their strong coupling with the spin singlets.
In recent experiments two-fold transport anisotropies have been reported inconsistent with the hexagonal symmetry of the underlying lattice.
We list possible scenarios of the two-fold symmetry based on pairing of conventional as well as unconventional symmetry.
Finally, I discuss the manifestations of the field induced topological phase transition in the 4 periodic current phase relation of the TMD based planar Josephson junctions.
These superconductors have an extremely anisotropic critical magnetic field with the parallel critical field far above the Pauli limit.
The mono-layer TMDs are non-centrosymmetric with strong spin-orbit interaction polarizing spins out-of-plane.
The spin-orbit interaction protects the conventional spin-singlet superconductivity against the pair breaking by the magnetic field.
We argue that in addition, the spin-orbit interaction mediates the transformation of singlet Cooper pairs into the triplet Cooper pairs by the applied field.
These parallel spin triplets are distinct from the anti-parallel spin triplets present at zero magnetic field.
Since the parallel spin triplets are field induced, they have a strong effect on the critical field.
Besides, these spin triplets are protected against the disorder scattering thanks to their strong coupling with the spin singlets.
In recent experiments two-fold transport anisotropies have been reported inconsistent with the hexagonal symmetry of the underlying lattice.
We list possible scenarios of the two-fold symmetry based on pairing of conventional as well as unconventional symmetry.
Finally, I discuss the manifestations of the field induced topological phase transition in the 4 periodic current phase relation of the TMD based planar Josephson junctions.