Magnetism driven by strong electronic correlations in the heavily carrier-doped iron oxypnictide LaFeAsO0.49H0.51

Abstract

The magnetism of the second antiferromagnetic phase (AF2) arising in the iron-based LaFeAsO 1−x H x superconductor for x 0.4 was investigated by muon spin rotation measurements under hydrostatic pressure up to 2.6 GPa. The Néel temperature (T N) obtained for a sample with x = 0.51 exhibits considerably greater sensitivity to pressure than that in the pristine antiferromagnetic phase (AF1; x 0.06). Moreover, while the AF1 phase is always accompanied by the structural transition (from tetragonal to orthorhombic) at a temperature (T s) which is slightly higher than T N , the AF2 phase prevails at higher pressures, above ∼1.5 GPa, where the structural transition is suppressed (T s = 0). These features indicate that the microscopic origin of the AF2 phase is distinct from that of AF1, suggesting that electronic correlation plays an important role in the former phase. We argue that the orbital-selective Mott transition is a plausible scenario to account for the observed pressure dependence of T N and T s in the AF2 phase.

Orbital Selectivity in Electron Correlations and Superconducting Pairing of Iron-Based Superconductors

“…Additional evidence for the OSMP has come from THz spectroscopy [122], Hall measurements [123], pump-probe spectroscopy [124], and highpressure transport measurements [125]. Moreover, a variety of other Fe-based systems have been studied for the orbital-selective Mott behavior [82][83][84][85][86][87]98]. We note in passing that related orbitalselective correlation effects have recently been discussed in the multiorbital 5f -based actinide systems [126,127].…”

“…Spectroscopy measurements have provided ample evidence that, for the parent compounds of the FeSCs, the incoherent part of the electron spectral weight (1 − w) is larger than the coherent counterpart w, which provides a microscopic definition of a bad metal. The full force of the electron correlations in the FeSCs has now become quite apparent [13,[81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97][98]. In leading toward this understanding, the orbital-selective aspects of the correlations and pairing have played an important role.…”