Heat Capacity-A Powerful Tool for Studying Exotic States of Matter

TL;DR

This tutorial demonstrates how heat capacity measurements serve as a versatile tool for investigating exotic quantum states of matter by analyzing thermodynamic contributions and phase transitions.

Contribution

It provides a practical guide for collecting, analyzing, and interpreting heat capacity data in modern quantum materials, bridging theory and experimental application.

Findings

Heat capacity captures contributions from lattice, electronic, and magnetic components.

Analysis of heat capacity reveals insights into phase transitions and excitations.

The tutorial covers methods for various exotic states like spin liquids and skyrmions.

Abstract

Heat capacity measurements are a powerful tool that researchers rely on when studying the relationship between microscopic degrees of freedom and macroscopic behavior in condensed matter. This uniqueness stems from heat capacity capturing contributions from lattice, electronic, and magnetic components, as well as energy-level populations, enabling an effective approach to studying phase transitions and excitations across different classes of materials. However, analyzing heat capacity data presents a common, appreciable challenge for new researchers. Although comprehensive theoretical aspects of heat capacity are presented in several elegant textbooks, practical application remains a daunting task. To overcome this challenge, this tutorial guides researchers in collecting, analyzing, and interpreting heat capacity data in contemporary quantum materials. We outline the connections between thermodynamics, heat capacity, and entropy, as well as measurement methodology and data analysis for representative examples, including phonon dynamics, spin waves, superconductors, magnetic skyrmions, proximate quantum spin liquids, and heavy-fermion materials. Our goal is to provide a concise, accessible guide that enables new researchers to utilize heat capacity as a quantitative lens for understanding exotic states of matter.