Extraordinary kinetic inductance of superconductor/ferromagnet/normal metal thin strip in an Fulde–Ferrell state

Journal of Physics: Condensed Matter. 2021. Vol. 33. No. 38. P. 385301.

Marychev P., Водолазов Д. Ю.

We have calculated kinetic inductance Lk of a thin superconductor/ferromagnet/normal metal strip in an in-plane Fulde–Ferrell (FF) state. We consider range of parameters when FF state appears at temperature TFF < Tc (Tc is a transition temperature to superconducting state) when the paramagnetic response of FN layers overcomes the diamagnetic response of S layer. We show that Lk diverges at T = TFF which is consequence of the second order phase transition to FF state, similar to divergency of Lk at T = Tc. Kinetic inductance also diverges at finite magnetic field at T < TFF which is consequence of magnetic field driven second order transition to/from FF state. Due to presence in the FF state finite supervelocity, at low current there are two states (metastable and ground) which have different Lk. Metastable state is unstable above some critical current which is much smaller than depairing current, above which the ground state becomes unstable. It results in strong dependence of Lk on current not only at large currents (near depairing current) but at low currents too. We argue that found properties could be useful in various applications which exploit temperature, current and magnetic field dependence of the kinetic inductance.

Keywords: кинетическая индуктивность, kinetic inductance, superconducting hybrid structures, сверхпроводящие гибридные структуры, Fulde–Ferrell–Larkin–Ovchinnikov state, состояние Фульде-Феррелла-Ларкина-Овчинникова