Possibility of local pair existence in optimally doped SmFeAsO(1-x) in pseudogap regime

TL;DR

This study investigates the pseudogap behavior in optimally doped SmFeAsO(0.85), revealing specific temperature-dependent features that suggest the possible existence of local pairs in the pseudogap regime, influenced by antiferromagnetic ordering.

Contribution

The paper provides the first analysis of pseudogap behavior in SmFeAsO(0.85) using resistivity data, linking it to antiferromagnetic transitions and theoretical models for AFM superconductors.

Findings

Pseudogap Delta* shows a non-monotonic temperature dependence with a minimum at about 120 K.

Delta*(T) decreases linearly below the structural transition at 147 K down to 133 K.

Behavior consistent with Machida, Nokura, and Matsubara theory for AFM superconductors.

Abstract

We report the analysis of pseudogap Delta* derived from resistivity experiments in FeAs-based superconductor SmFeAsO(0.85), having a critical temperature T_c = 55 K. Rather specific dependence Delta*(T) with two representative temperatures followed by a minimum at about 120 K was observed. Below T_s = 147 K, corresponding to the structural transition in SmFeAsO, Delta*(T) decreases linearly down to the temperature T_AFM = 133 K. This last peculiarity can likely be attributed to the antiferromagnetic (AFM) ordering of Fe spins. It is believed that the found behavior can be explained in terms of Machida, Nokura, and Matsubara (MNM) theory developed for the AFM superconductors.