Phase diagram of dipolar bosons in 2D with tilted polarization

TL;DR

This study maps the phase diagram of 2D dipolar bosons with tilted polarization, revealing superfluid, solid, and stripe phases, and characterizing the second-order quantum phase transition between gas and stripe phases.

Contribution

It provides a comprehensive analysis of how tilt angle and density influence phase transitions in dipolar bosons, highlighting the emergence of a stripe phase due to anisotropic interactions.

Findings

Identification of superfluid, solid, and stripe phases

Stripe phase induced at large tilt angles

Second-order phase transition with estimated critical exponents

Abstract

We analyze the ground state of a system of dipolar bosons moving in the $XY$ plane and such that their dipolar moments are all aligned in a fixed direction in space. We focus on the general case where the polarization field forms a generic angle $\alpha$ with respect to the $Z$ axis. We use the Path Integral Ground State method to analyze the static properties of the system as both $\alpha$ and the density $n$ vary over a wide range were the system is stable. We use the maximum of the static structure function as an order parameter to characterize the different phases and the transition lines among them. We find that aside of a superfluid gas and a solid phase, the system reaches a stripe phase at large tilting angles that is entirely induced by the anisotropic character of the interaction. We also show that the quantum phase transition from the gas to the stripe phase is of second order, and report approximate values for the critical exponents.