Pressure-dependent magnetization and magnetoresistivity studies on the   tetragonal FeS (mackinawite): revealing its intrinsic metallic character
  The transport and magnetic properties of the tetragonal Fe$_{1+\delta}$S were investigated using magnetoresistivity and magnetization within 2$\leq T\leq $300 K, $H\leq$70 kOe and $P\leq$ 3.0 GPa. In addition, room-temperature X-ray diffraction and photoelectron spectroscopy were also applied. In contrast to previously reported nonmetallic character, Fe$_{1+\delta}$S is intrinsically metallic but due to a presence of a weak localization such metallic character is not exhibited below room temperature. An applied pressure reduces strongly this additional resistive contribution and as such enhances the temperature range of the metallic character which, for $\sim$3 GPa, is evident down to 75 K. The absence of superconductivity as well as the mechanism behind the weak localization will be discussed. 
S. J. Denholme, H. Okazaki, S. Demura, K. Deguchi, M. Fujioka, T.   Yamaguchi, H. Takeya, M. ElMassalami, H. Fujiwara, T. Wa...
cond-mat.str-el cond-mat.supr-con