# $XY$ model with antinematic interaction

## TL;DR

This paper investigates the $XY$ model with mixed ferromagnetic and antinematic interactions, revealing a new canted ferromagnetic phase with unique ordering properties and mapping out the phase diagram based on interaction ratios.

## Contribution

It introduces a novel canted ferromagnetic phase in the $XY$ model with competing interactions and characterizes its properties and phase transitions.

## Key findings

- Identification of a canted ferromagnetic QLRO phase
- Characterization of non-universal canting angles
- Phase diagram as a function of interaction ratio

## Abstract

We consider the $XY$ model with ferromagnetic (FM) and antinematic (AN) nearest-neighbor interactions on a square lattice for a varying interaction strength ratio. Besides the expected FM and AN quasi-long-range order (QLRO) phases we identify at low temperatures another peculiar canted ferromagnetic (CFM) QLRO phase, resulting from the competition between the collinear FM and non-collinear AN ordering tendencies. In the CFM phase neighboring spins that belong to different sublattices are canted by a non-universal (dependent on the interaction strength ratio) angle and the ordering is characterized by a fast-decaying power-law intra-sublattice correlation function. Compared to the FM phase, in the CFM phase correlations are significantly diminished by the presence of zero-energy domain walls due to the inherent degeneracy caused by the AN interactions. We present the phase diagram as a function of the interaction strength ratio and discuss the character of the respective phases as well as the transitions between them.