Interplay of uniform U(1) quantum spin liquid and magnetic phases in rare earth pyrochlore magnets : a fermionic parton approach

TL;DR

This paper investigates the stability and properties of a uniform U(1) quantum spin liquid in rare earth pyrochlore magnets, revealing fractionalized magnetic phases and their signatures in neutron scattering.

Contribution

It introduces an augmented fermionic parton mean field theory to analyze the interplay of quantum spin liquids and magnetic phases in pyrochlore magnets, highlighting new fractionalized phases and topological features.

Findings

Stable uniform U(1) QSL with gapped and gapless excitations

Identification of fractionalized magnetic ordered phases with topological properties

Explanation of diffuse neutron scattering in rare-earth pyrochlores

Abstract

We study the uniform time reversal invariant $U(1)$ quantum spin liquid (QSL) with low energy fermionic quasi-particles for rare earth pyrochlore magnets and explore its magnetic instability employing an augmented fermionic parton mean field theory approach. Self consistent calculations stabilise an uniform $U(1)$ QSL with both gapped and gapless parton excitations as well as fractionalised magnetically ordered phases in an experimentally relevant part of the phase diagram near the classical phase boundaries of the magnetically ordered phases. The gapped QSL has a band-structure with a non-zero $Z_2$ topological invariant. The fractionalised magnetic ordered phases bears signature of both QSL through fermionic excitations as well as magnetic order. Thus this provides a possible way to understand the unconventional diffuse neutron scattering in rare-earth pyrochlores such as Yb$_2$Ti$_2$O$_7$, Er$_2$Sn$_2$O$_7$ and Er$_2$Pt$_2$O$_7$ at low/zero external magnetic fields. We calculate the dynamic spin structure factor to understand the nature of the diffuse two-particle continuum.