Superconducting critical field far above the Pauli limit in   one-dimensional Li$_{0.9}$Mo$_6$O$_{17}$
  The upper critical field $H_{c2}$ of purple bronze Li$_{0.9}$Mo$_6$O$_{17}$ is found to exhibit a large anisotropy, in quantitative agreement with that expected from the observed electrical resistivity anisotropy. With the field aligned along the most conducting axis, $H_{c2}$ increases monotonically with decreasing temperature to a value five times larger than the estimated paramagnetic pair-breaking field. Theories for the enhancement of $H_{c2}$ invoking spin-orbit scattering or strong-coupling superconductivity are shown to be inadequate in explaining the observed behavior, suggesting that the pairing state in Li$_{0.9}$Mo$_6$O$_{17}$ is unconventional and possibly spin-triplet. 
J.-F. Mercure, A. F. Bangura, Xiaofeng Xu, N. Wakeham, A. Carrington,   P. Walmsley, M. Greenblatt and N. E. Hussey
cond-mat.supr-con cond-mat.str-el