Linus Aliani | Searcharxiv

arXiv2025

Cooling of electrons via superconducting tunnel junctions and their arrays exhibiting nodal lines

We study theoretically a process of cooling electrons using a superconducting tunnel junction with a $\pi$ phase difference and a usual insulator or a ferroelectric in-between, and an array of such junctions with ferroelectric layers in-between. These setups have a complex structure of entropy due to nodal lines, where the density of states can be divergent or larger than for a free electron gas at a chemical potential level. We consider a small current running from the bath of electrons through the setup, where electrons have to have higher entropy, and thus remove heat from the bath.

cond-mat.mes-hall↗

arXiv2024

Meissner effect in non-Hermitian superconductors

We study theoretically Meissner effect in non-Hermitian systems of BCS type, i.e., with an electron-electron interaction leading to the mean field description in a Cooper channel, via superfluid stiffness. We show that depending on the values of the mean fields, chemical potential, and temperature, we obtain paramagnetic or diamagnetic Meissner effect. Notably, positive real part of the product of mean fields guarantees diamagnetic Meissner effect in an $s$-wave 3D non-Hermitian superconductor. Once the mean fields are close to being anti-Hermitian, 2D $s$-, $p_x$-, and $d$-wave superconductors exhibit interesting behaviour, including negative superfluid stiffness giving paramagnetic Meissner effect for certain parameters. Negative superfluid stiffness indicates instability of this collective state.

cond-mat.supr-con↗