Spin excitations in disordered spin systems

• Grant number: 23/06682-8
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: September 01, 2023
• End date: August 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Eric de Castro e Andrade
• Grantee: Rafael Marques Paes Teixeira
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/06629-4 - Electronic correlations in quantum materials: inhomogeneities and frustration, AP.JP2

Abstract

The quenched disorder is inevitably present in every real solid in the form of structural or substitutional defects. In frustrated systems, this can strongly influence low-energy behavior because of their tendency to phase competition and large low-temperature entropies. We may then expect novel magnetic states which find no realization in their unfrustrated counterpart, like spiral magnetic order, or even states without long-range magnetic order, like spin-liquids, spin-glasses, and valence-bond solids. As a particular example, we will focus on the compound YbMgGaO4, a recently discovered triangular lattice spin-1/2 insulator initially proposed to be a quantum spin liquid. With growing experimental evidence that disorder is intrinsic to this system, alternative theories were put forward, interpreting this material in terms of a valence bond glass. In this work, we want to contrast these two scenarios to a semiclassical polarized cluster spin-glass state we recently proposed. This is an important step to increase our understanding of the possible ground states for a disordered frustrated magnet in two dimensions. (AU)