# Magnetic signatures of quantum critical points of the ferrimagnetic mixed spin-(1/2, S) Heisenberg chains at finite temperatures

## TL;DR

This study investigates the magnetic signatures of quantum critical points in ferrimagnetic mixed spin-(1/2,S) Heisenberg chains at finite temperatures using quantum Monte Carlo and DMRG methods, revealing characteristic behaviors near criticality.

## Contribution

It provides new insights into finite-temperature magnetic signatures of quantum critical points in mixed spin chains, combining Monte Carlo and DMRG techniques.

## Key findings

- Quantum critical points identified at finite temperatures.
- Magnetization exhibits square-root behavior near critical points.
- Susceptibility and entropy show distinct maxima and minima at criticality.

## Abstract

Magnetic properties of the ferrimagnetic mixed spin-(1/2,S) Heisenberg chains are examined using quantum Monte Carlo simulations for two different quantum spin numbers S = 1 and 3/2. The calculated magnetization curves at finite temperatures are confronted with zero-temperature magnetization data obtained within density-matrix renormalization group method, which imply an existence of two quantum critical points determining a breakdown of the gapped Lieb-Mattis ferrimagnetic phase and Tomonaga-Luttinger spin-liquid phase, respectively. While a square-root behavior of the magnetization accompanying each quantum critical point is gradually smoothed upon rising temperature, the susceptibility and isothermal entropy change data provide a stronger evidence of the quantum critical points at finite temperatures through marked local maxima and minima, respectively.