# Phase Diagram for a model of Spin-Crossover in Molecular Crystals

## TL;DR

This paper introduces a simple theoretical model for spin-crossover in molecular crystals, analyzing its phase diagram through mean field and Monte Carlo methods to understand the transition behaviors and hysteresis phenomena.

## Contribution

It provides a combined mean field and Monte Carlo analysis of a new model for spin-crossover, elucidating the phase diagram and transition properties.

## Key findings

- Good agreement between analytical and simulation results in certain parameter regions
- Mean field approach breaks down where correlations and cooperativity are significant
- Model captures key features like abrupt, gradual, and incomplete transitions

## Abstract

Spin-crossover has a wide range of applications from memory devices to sensors. This has to do mainly with the nature of the transition, which may be abrupt, gradual or incomplete and may also present hysteresis. This transition alters the properties of a given sample, such as magnetic moment, color and electric resistance to name some. Yet, a thorough understanding of the phenomenon is still lacking. In this work a simple model is provided to mimic some of the properties known to occur in spin-crossover. A detailed study of the model parameters is presented using a mean field approach and exhaustive Monte Carlo simulations. A good agreement is found between the analytical results and the simulations for certain regions in the parameter-space. This mean field approach breaks down in parameter regions where the correlations and cooperativity may no longer be averaged over.