Structural and Magnetic Phase Transitions in NdCoAsO under High   Pressures
  We have investigated structural and magnetic phase transitions under high pressures in a quaternary rare earth transition metal arsenide oxide NdCoAsO compound that is isostructural to high temperature superconductor NdFeAsO. Four-probe electrical resistance measurements carried out in a designer diamond anvil cell show that the ferromagnetic Curie temperature and anti-ferromagnetic Neel temperature increase with an increase in pressure. High pressure x-ray diffraction studies using a synchrotron source show a structural phase transition from a tetragonal phase to a new crystallographic phase at a pressure of 23 GPa at 300 K. The NdCoAsO sample remained anti-ferromagnetic and non-superconducting to temperatures down to 10 K and to the highest pressure achieved in this experiment of 53 GPa. A P-T phase diagram for NdCoAsO is presented to a pressure of 53 GPa and low temperatures of 10 K. 
Walter Uhoya, Georgiy M. Tsoi, Yogesh K. Vohra, Michael A. McGuire,   Athena S. Sefat, Brian C. Sales, David Mandrus and Sam...
cond-mat.supr-con cond-mat.mtrl-sci cond-mat.other