1205.6730 (E. Hassinger et al.)

New Phase Induced by Pressure in the Iron-Arsenide Superconductor
K-Ba122    [PDF]

E. Hassinger, F. Valade, S. Rene de Cotret, A. Juneau-Fecteau, J. -Ph. Reid, H. Kim, M. A. Tanatar, R. Prozorov, B. Shen, H. -H. Wen, N. Doiron-Leyraud, Louis Taillefer

The electrical resistivity of the iron-arsenide superconductor Ba{1-x}KxFe2As2 was measured in applied pressures up to 2.5 GPa for two underdoped samples, with x = 0.16 and x = 0.18. The antiferromagnetic ordering temperature T_N, detected as a sharp anomaly in the resistivity, decreases linearly with pressure. At pressures above P = 1.0 GPa, a second anomaly is detected at a lower temperature T_0, which rises with pressure. We attribute this second anomaly to the onset of a phase that causes a reconstruction of the Fermi surface. The superconducting transition temperature T_c rises with pressure until the new phase sets in, and then it drops as T_0 grows. This shows that the new phase competes with superconductivity. We discuss two possible orders that could set in at T_0: an incommensurate charge-density wave, and a second spin-density wave, with a Q vector different from that of the first spin-density wave that sets in at T_N.

View original: http://arxiv.org/abs/1205.6730