From (pi, 0) magnetic order to superconductivity with (pi, pi) magnetic resonance in Fe1.02(Te1-xSex)

TL;DR

This study investigates how doping transforms magnetic order in Fe1.02(Te1-xSex), leading to superconductivity associated with a (pi, pi) magnetic resonance, revealing a shared magnetic origin in iron-based superconductors.

Contribution

It demonstrates the evolution from (pi, 0) magnetic order to (pi, pi) magnetic resonance associated with superconductivity in Fe1.02(Te1-xSex).

Findings

Magnetic soft mode linked to weak charge localization.

Superconductivity emerges as (pi, pi) magnetic mode dominates.

Shared magnetic origin for superconductivity in iron chalcogenides and pnictides.

Abstract

The iron chalcogenide Fe1+y(Te1-xSex) is structurally the simplest of the Fe-based superconductors. Although the Fermi surface is similar to iron pnictides, the parent compound Fe1+yTe exhibits antiferromagnetic order with in-plane magnetic wave-vector (pi, 0). This contrasts the pnictide parent compounds where the magnetic order has an in-plane magnetic wave-vector (pi, pi) that connects hole and electron parts of the Fermi surface. Despite these differences, both the pnictide and chalcogenide Fe-superconductors exhibit superconducting spin resonances around (pi, pi), suggesting a common symmetry for their superconducting order parameter. A central question in this burgeoning field is therefore how (pi, pi) superconductivity can emerge from a (pi, 0) magnetic instability. Here, we report that the magnetic soft mode evolving from the (pi, 0)-type magnetic long-range order is associated with weak charge carrier localization. Bulk superconductivity occurs only as the magnetic mode at (pi, pi) becomes dominant upon doping. Our results suggest a common magnetic origin for superconductivity in iron chalcogenide and pnictide superconductors.