Excitations of a binary dipolar supersolid

TL;DR

This paper predicts a complex excitation spectrum in a binary dipolar supersolid, revealing multiple Goldstone modes, phonon branches, and a spin-Higgs mode, advancing understanding of supersolid collective excitations.

Contribution

It introduces a detailed theoretical prediction of the excitation spectrum, including Goldstone, phonon, and spin-Higgs modes, in a binary dipolar supersolid with a crystal structure.

Findings

Identification of three Goldstone branches with different sound characters

Splitting of the lattice branch into optical and acoustic phonons

Discovery of a spin-Higgs mode related to supersolid modulation

Abstract

We predict a rich excitation spectrum of a binary dipolar supersolid in a linear crystal geometry, where the ground state consists of two partially immiscible components with alternating, interlocking domains. We identify three Goldstone branches, each with first-sound, second-sound or spin-sound character. In analogy with a diatomic crystal, the resulting lattice has a two-domain primitive basis and we find that the crystal (first-sound-like) branch is split into optical and acoustic phonons. We also find a spin-Higgs branch that is associated with the supersolid modulation amplitude.