Magnetic determination of Hc2 under accurate alignment in (TMTSF)2ClO4 -: art. no. 067001

Cantilever magnetometry has been used to measure the upper critical magnetic field H-c2 of the quasi-one-dimensional molecular organic superconductor (TMTSF)(2)ClO4. From simultaneous resistivity and torque magnetization experiments conducted under precise field alignment, H-c2 at low temperature is shown to reach 5 T, 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.