# Phase Transition in a Long Range Antiferromagnetic Model

## TL;DR

This paper investigates a long-range antiferromagnetic Ising model under a transverse magnetic field, revealing a second-order quantum phase transition at zero temperature and a thermal transition at higher temperatures, with novel derivations.

## Contribution

It introduces a perturbative approach to analyze phase transitions in a long-range antiferromagnetic Ising model, providing insights not accessible from existing models.

## Key findings

- Second-order quantum phase transition at zero temperature
- Thermal phase transition to disordered phase with increasing temperature
- Perturbative derivation of phase transition features

## Abstract

We consider an Ising model where longitudinal components of every pair of spins have antiferromagnetic interaction of the same magnitude. When subjected to a transverse magnetic field at zero temperature, the system undergoes a phase transition of second order to an ordered phase and if the temperature is now increased, there is another phase transition to disordered phase. We provide derivation of these features by perturbative treatment up to the second order and argue that the results are non-trivial and not derivable from the known results about related models.