Super Solid Categories
Contents
Introduction
Motivation
The purpose of this page is to attempt a categorization of the various phases called ``supersolid, and to sort different physical systems into those categories.
Definition
A supersolid is a system showing spontaneously broken translational symmetry (the solid), coexisting with superfluidity, or alternatively broken gauge symmetry.
Categories
I. Continuum supersolids
Category I supersolids are continuos space systems, were a continuous translation symmetry is broken down to a discrete symmetry.
I.A Single species supersolids
I.A.1 Andreev-Lifshitz type
Definition: few atoms per unit cell in the solid, and superfluidity of vacancies and interstitials
Examples: none known
I.A.2 Gross type
Definition: superfluid droplets forming a crystal
Examples:
- ...
- ...
I.B Multi-component supersolids
I.B.1 Purely bosonic mixtures
Definition: a mixture of bosonic particles
Examples:
- any known?
I.B.2 Bose-fermi mixtures with superfluid bosons
Definition: a mixture of bosonic and fermionic particles, where only bosonic particles become superfluid
Examples:
- any known?
I.B.2 Mixtures with superfluid fermions
Definition: a mixture of bosonic and fermionic species, where some of the fermions form superfluid Cooper pairs
Examples:
- all superconducting crystals
II. Lattice supersolids
Category II supersolids are lattice systems, were a discrete translation symmetry is spontaneously broken down further,
II.A Single species supersolids
II.A.1 Andreev-Lifshitz type
Definition: few atoms per unit cell in the solid, and superfluidity of vacancies and interstitials
Examples:
- bosons with nearest neighbor or dipolar repulsion on a triangular lattice
- bosons with nearest neighbor repulsion on a face centered cubic lattice
II.A.2 Gross type
Definition: superfluid droplets forming a crystal
Examples:
- ...
- ...
II.B Multi-component supersolids
II.B.1 Purely bosonic mixtures
Definition: a mixture of bosonic particles
Examples:
- two-species bosonic mixtures on a square or cubic lattice
II.B.2 Bose-fermi mixtures with superfluid bosons
Definition: a mixture of bosonic and fermionic particles, where only bosonic particles become superfluid
Examples:
- Büchler-Blatter
II.B.2 Mixtures with superfluid fermions
Definition: a mixture of bosonic and fermionic species, where some of the fermions form superfluid Cooper pairs
Examples:
- any known?
= III. Other supersolids
Non-supersolids
While there is a broad scope for interpretation, there are a number of systems that cannot be labeled a supersolid. These include the systems discussed below
Phase separation
Some systems separate into solid and superfluid phases in different regions of space. Even if it is the same component this cannot be called a supersolid.
