# Magnetic phase separation in a frustrated ferrimagnetic chain under a magnetic field

## TL;DR

This paper investigates a first-order quantum phase transition in a frustrated ferrimagnetic chain under a magnetic field, revealing phase separation, magnetization jumps, and the role of singlet pairs using density matrix renormalization group methods.

## Contribution

It introduces a detailed analysis of phase separation and transition characteristics in a frustrated ferrimagnetic chain under magnetic field, highlighting the role of singlet pairs and identifying critical points.

## Key findings

- Magnetization curve shows a macroscopic jump indicating a first-order transition.
- Energy landscape has two minima corresponding to competing phases.
- Transition involves an increase in itinerant singlet pairs.

## Abstract

We use density matrix renormalization group to study the first-order quantum phase transition induced by a magnetic field $h$ in a frustrated ferrimagnetic chain. The magnetization ($m$) curve as a function of $h$ presents a macroscopic jump and the energy curve as a function of $m$ has two global minima. We characterize the two competing phases and study the phase-separated states in the coexistence region. Also, we observe that the transition is accompanied by an increase in the number of itinerant singlet pairs between sites in the unit cells of the chain. Finally, we identify the critical point at the end of the first-order transition line and a crossover line.