Pseudogaps and Charge Band in the Parisi Solution of Insulating and Superconducting Electronic Spin Glasses at Arbitrary Fillings

TL;DR

This paper explores the complex electronic structure and phase transitions in fermionic Ising spin glasses with arbitrary fillings, revealing a multi-band structure and the interplay between spin glass order and superconductivity.

Contribution

It provides a detailed analysis of the phase structure and band formation in spin glasses, including the effects of replica symmetry breaking and competition with superconductivity.

Findings

Emergence of a multi-band structure below the freezing temperature.

Identification of a nonmagnetic central band separated by gaps at T=0.

Gaps tend to zero as replica symmetry breaking increases.

Abstract

We report progress in understanding the fermionic Ising spin glass with arbitrary filling. A crossover from a magnetically disordered single band phase via two intermediate bands just below the freezing temperature to a 3-band structure at still lower temperatures - beyond an almost random field instability - is shown to emerge in the magnetic phase. An attempt is made to explain the exact solution in terms of a quantum Parisi phase. A central nonmagnetic band is found and seen to become sharply separated at T=0 by gaps from upper and lower magnetic bands. The gap sizes tend towards zero as the number of replica symmetry breaking steps increases towards infinity. In an extended model, the competition between local pairing superconductivity and spin glass order is discussed.