Pressure-induced magnetism in the iron-based superconductors AFe2As2 ( A=K , Cs, Rb)

Abstract

The magnetic properties of iron-based superconductors AFe 2 As 2 (A = K, Cs, and Rb), which are characterized by the V-shaped dependence of the critical temperature (T c) on pressure (P), were studied by means of the muon spin rotation/relaxation technique. In all three systems studied the magnetism was found to appear for pressures slightly below the critical one (P c), i.e., at pressure where T c (P) changes the slope. Rather than competing, magnetism and superconductivity in AFe 2 As 2 are coexisting at the P P c pressure region. Our results support the scenario of a transition from one pairing state to another, with different symmetries on either side of P c .