Supersolid states in a spin system-phase diagram and collective excitations

TL;DR

This paper explores the phase diagram and collective excitations of a frustrated spin-1/2 system, revealing a supersolid phase and unique states with potential experimental detection via neutron scattering.

Contribution

It provides the first detailed phase diagram of a frustrated dimer spin system and analyzes collective excitations, including a novel phase absent in Bose Hubbard models.

Findings

Identification of a supersolid phase in the spin system

Derivation of an analytic spin wave velocity expression

Prediction of neutron scattering signatures of excitations

Abstract

Phases analogous to supersolids can be realized in spin systems. Here we obtain the phase diagram of a frustrated dimer spin-1/2 system on a square lattice and study the collective excitation spectra, focusing on the supersolid state (SS). In the phase diagram on a parameter space of the exchange interaction and magnetic field, we find, on top of the SS phase, a phase that has no counterpart in the Bose Hubbard model and this state becomes dominant at the region where the enhancement of SS occurs in the bose Hubbard model. We then investigate the excitation spectrum and spin- spin correlation, which can be detected by neutron scattering experiments. We obtain an analytic expression for the spin wave velocity, which agrees with hydrodynamic relations. The intensity of excitation modes in the spin-spin correlation function is calculated and their change in the supersolid and superfluid states is discussed.