Effect of impurities on supersolid condensate: a Ginzburg-Landau approach

TL;DR

This paper develops a Ginzburg-Landau model for supersolids incorporating both density and superfluid order parameters, analyzing how impurities like 3He affect the phase's properties and stability.

Contribution

It introduces a Ginzburg-Landau functional for supersolids with two order parameters and explores impurity effects on supersolid behavior.

Findings

Adding 3He creates attractive regions for vacancies, increasing local T_c.

3He impurities reduce supersolid stiffness in a linear fashion.

Impurities induce granular structures affecting supersolid properties.

Abstract

Basing our arguments on a wave function that contains both positional and superfluid order, we propose a Ginzburg-Landau functional for a supersolid with the two order parameters necessary to describe such a phase: density n_B(r) and supersolid order parameter \psi_V. We argue that adding lighter $^3$He atoms to a 4He supersolid produces attractive regions for vacancies, leading to patches of higher T_c. On the other hand, the supersolid stiffness decreases in this granular state with increased 3He disorder. Both effects are linear in 3He concentration.