Magnon-induced superconductivity in field-cooled spin-1/2 antiferromagnets

TL;DR

This paper proposes a mechanism where magnon interactions in field-cooled spin-1/2 antiferromagnets induce p-wave superconductivity at a specific quantum critical point, coexisting with magnetic order.

Contribution

It introduces a novel insulator-metal transition and superconductivity mechanism driven by magnon-electron interactions in field-cooled antiferromagnets.

Findings

Superconductivity occurs at the quantum partial order point (QPOP).

Magnon-electron interactions induce p-wave superconductivity.

Material transitions from insulator to metal with increasing magnetic field.

Abstract

If, during the preparation, an external magnetic field is applied upon cooling we say it has been field cooled. A novel mechanism for insulator-metal transition and superconductivity in field-cooled spin-$1/2$ antiferromagnets on bcc lattice is discussed. Applying a magnetic field along the sublattice B magnetization, we change the magnetic and transport properties of the material. There is a critical value $H_{cr1}$. When the magnetic field is below the critical one $H<H_{cr1}$ the prepared material is a spin$-1/2$ antiferromagnetic insulator. When $H>H_{cr1}$ the sublattice A electrons are delocalized and the material is metal. There is a second critical value $H_{cr2}>H_{cr1}$. When $H=H_{cr2}$, it is shown that the Zeeman splitting of the sublattice A electrons is zero and they do not contribute to the magnetization of the system. At this quantum partial order point (QPOP) the sublattice B transversal spin fluctuations (magnons) interact with sublattice A electrons inducing spin anti-parallel \emph{p}-wave superconductivity which coexists with magnetism. At zero temperature the magnetic moment of sublattice B electrons is maximal. Below the N\'{e}el temperature $(T_N)$ the gap is approximately constant with a small increase when the system approaches $T_N$. It abruptly falls down to zero at temperatures above $T_N$.