Andrey Chubukov

Mar 14, 2024 | nature.com | Andrey Chubukov

AbstractWe analyze superconductivity in a multi-orbital fermionic system near the onset of a nematic order, using doped FeSe as an example. We associate nematicity with spontaneous polarization between dxz and dyz orbitals. We derive pairing interaction, mediated by soft nematic fluctuations, and show that it is attractive, and its strength depends on the position on the Fermi surface.

Oct 13, 2023 | link.aps.org | Zhiyu Dong |Leonid S. Levitov |Andrey Chubukov

Spin excitations that soften near the onset of magnetic order have long been known to act as “paramagnon” pairing glue that can drive superconductivity. Recent findings of superconductivity in graphene bilayers and trilayers, occurring in the proximity of different itinerant ordered phases polarized in isospin (spin and valley), have motivated us to conduct a comprehensive study of an isospin extension of the paramagnon pairing mechanism in the vicinity of different isospin orders.

May 11, 2023 | link.aps.org | Zhiyu Dong |Andrey Chubukov |Leonid S. Levitov

Abstract We consider the origin of superconductivity found recently in Bernal bilayer graphene at the onset of isospin-polarized order, trying to infer the pairing mechanism and superconducting order from the measurements available to date. The superconductivity is induced by a parallel magnetic field and persists well above the Pauli limit, indicating an unconventional scenario of quantum-critical pairing, where soft fluctuations of isospin give rise to spin-triplet superconductivity.