Magnetic Determination of $H_{c2}$ under Accurate Alignment in (TMTSF)$_2$ClO$_4$

TL;DR

This study uses cantilever magnetometry with precise field alignment to measure the upper critical magnetic field in (TMTSF)$_2$ClO$_4$, revealing a value nearly twice the Pauli limit and supporting spin triplet pairing.

Contribution

First thermodynamic measurement of $H_{c2}$ in (TMTSF)$_2$ClO$_4$ with accurate alignment, indicating unconventional superconductivity.

Findings

$H_{c2}$ reaches 5T at low temperature

Results support spin triplet pairing hypothesis

Provides thermodynamic evidence for large $H_{c2}$

Abstract

Cantilever magnetometry has been used to measure the upper critical magnetic field $H_{c2}$ of the quasi-one dimensional molecular organic superconductor (TMTSF)$_2$ClO$_4$. From simultaneous resistivity and torque magnetization experiments conducted under precise field alignment, $H_{c2}$ at low temperature is shown to reach 5T, nearly twice the Pauli paramagnetic limit imposed on spin singlet superconductors. These results constitute the first thermodynamic evidence for a large $H_{c2}$ in this system and provide support for spin triplet pairing in this unconventional superconductor