# Multidimensional entropy landscape of quantum criticality

## TL;DR

This paper explores the multidimensional entropy landscape near quantum critical points, linking thermodynamic principles with quantum fluctuations to understand phase transitions and the emergence of novel phases like high-temperature superconductivity.

## Contribution

It introduces a general thermodynamic framework to map the entropy landscape around quantum critical points, demonstrated on CeCu6-xAux, connecting stress dependence to quantum fluctuations.

## Key findings

- Entropy peaks near quantum critical points in multidimensional stress space
- Directional stress dependence of entropy correlates with quantum critical fluctuations
- Framework lays foundation for understanding nucleation of novel quantum phases

## Abstract

The Third Law of Thermodynamics states that the entropy of any system in equilibrium has to vanish at absolute zero temperature. At nonzero temperatures, on the other hand, matter is expected to accumulate entropy near a quantum critical point (QCP), where it undergoes a continuous transition from one ground state to another. Here, we determine, based on general thermodynamic principles, the spatial-dimensional profile of the entropy S near a QCP and its steepest descent in the corresponding multidimensional stress space. We demonstrate this approach for the canonical quantum critical compound CeCu6-xAux near its onset of antiferromagnetic order. We are able to link the directional stress dependence of S to the previously determined geometry of quantum critical fluctuations. Our demonstration of the multidimensional entropy landscape provides the foundation to understand how quantum criticality nucleates novel phases such as high-temperature superconductivity.

---
Source: https://tomesphere.com/paper/1812.02940