Upper critical field and pairing symmetry of Ising superconductors

Fuente: arXiv
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Autori principali: Engström, Lena, Zullo, Ludovica, Cren, Tristan, Mesaros, Andrej, Simon, Pascal
Natura: Preprint
Pubblicazione: 2025
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author Engström, Lena
Zullo, Ludovica
Cren, Tristan
Mesaros, Andrej
Simon, Pascal
author_facet Engström, Lena
Zullo, Ludovica
Cren, Tristan
Mesaros, Andrej
Simon, Pascal
contents Motivated by the fact that the measured critical field $H_{c2}$ in various transition metal dichalcogenide (TMD) superconductors is poorly understood, we reexamine its scaling behavior with temperature and spin-orbit coupling (SOC). By computing the spin-susceptibility in a multipocket system, we find that segments of the Fermi Surface (FS) at which the SOC has nodal points can have a contribution orders of magnitude larger than the remaining FS, hence setting the $H_{c2}$, assuming the presence of a conventional singlet superconducting order parameter. Nodal lines of an Ising SOC in the Brillouin zone are imposed by symmetry, so they cause such nodal points whenever they intersect an FS pocket, which is indeed the case in monolayer NbSe$_2$ and TaS$_2$, but not in gated MoS$_2$ and WS$_2$. Our analysis reinterprets existing measurements, concluding that a dominant singlet-order parameter on pockets with SOC nodes is consistent with the $H_{c2}(T)$ data for all monolayer Ising superconductors, in contrast to previous contradictory pairing assumptions. Finally, we predict a doping-dependent experimental signature of our theory.
format Preprint
id arxiv_https___arxiv_org_abs_2504_20775
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Upper critical field and pairing symmetry of Ising superconductors
Engström, Lena
Zullo, Ludovica
Cren, Tristan
Mesaros, Andrej
Simon, Pascal
Superconductivity
Motivated by the fact that the measured critical field $H_{c2}$ in various transition metal dichalcogenide (TMD) superconductors is poorly understood, we reexamine its scaling behavior with temperature and spin-orbit coupling (SOC). By computing the spin-susceptibility in a multipocket system, we find that segments of the Fermi Surface (FS) at which the SOC has nodal points can have a contribution orders of magnitude larger than the remaining FS, hence setting the $H_{c2}$, assuming the presence of a conventional singlet superconducting order parameter. Nodal lines of an Ising SOC in the Brillouin zone are imposed by symmetry, so they cause such nodal points whenever they intersect an FS pocket, which is indeed the case in monolayer NbSe$_2$ and TaS$_2$, but not in gated MoS$_2$ and WS$_2$. Our analysis reinterprets existing measurements, concluding that a dominant singlet-order parameter on pockets with SOC nodes is consistent with the $H_{c2}(T)$ data for all monolayer Ising superconductors, in contrast to previous contradictory pairing assumptions. Finally, we predict a doping-dependent experimental signature of our theory.
title Upper critical field and pairing symmetry of Ising superconductors
topic Superconductivity
url https://arxiv.org/abs/2504.20775