Transverse Magnetic Response from Orbitally Polarized Cooper Pairs in Elemental Superconductors

TL;DR

This paper reveals how strain-induced symmetry lowering in elemental superconductors enables orbitally polarized Cooper pairs, leading to a unique transverse magnetic response detectable experimentally.

Contribution

It demonstrates that symmetry lowering activates interorbital pairing and results in a novel magnetic response in strained elemental superconductors.

Findings

Symmetry lowering activates interorbital pairing in bulk and surface.

A transverse magnetic response emerges due to orbitally polarized Cooper pairs.

Orbital magnetization appears perpendicular to in-plane magnetic fields.

Abstract

We demonstrate how crystalline symmetry lowering, as for instance through strain, allows elemental superconductors such as vanadium and niobium to realize spin-singlet orbitally polarized Cooper pairs composed of electrons with identical orbital moments. Using superconducting density functional theory, we show that lowering of trigonal symmetry to $C_s$, thus keeping only a single mirror plane, activates interorbital pairing in bulk and (111) surfaces, with a pronounced surface enhancement. In a magnetic field, the resulting orbitally polarized superconducting state leads to a novel transverse magnetic response. For in--plane field orientations that break the remaining mirror symmetry, a sizable orbital magnetization emerges perpendicular to the applied field. We show that this effect is a direct consequence of equal--orbital-moment Cooper pairing, providing an experimentally accessible signature of this state. Our results establish strained elemental superconductors as a minimal material platform for superconducting orbitronics.