# The role of the entropy in the ground state formation of magnetically frustrated systems within their quantum critical regime

## TL;DR

This paper investigates how entropy influences the ground state formation in magnetically frustrated systems near quantum critical points, revealing universal thermodynamic behaviors and entropy constraints.

## Contribution

It provides an empirical analysis of entropy trajectories and thermodynamic properties in frustrated systems, highlighting universal features and differences from standard non-Fermi-liquids.

## Key findings

- A common $C_m/T$ plateau at very low temperatures in Yb-based compounds
- Differences between VHF and non-Fermi-liquid behaviors
- Entropy-bottlenecks influence ground state transitions

## Abstract

A systematic modification of the entropy trajectory $S_m(T)$ is observed at very low temperature in magnetically frustrated systems as a consequence of the constraint $S_m\geq 0$ imposed by the third law of thermodynamics. The lack of magnetic order allows to explore some unusual thermodynamic properties by tracing the physical behavior of real systems. The most relevant findings are: i) a common $C_m/T|_{T\to 0} \approx 7$\,J/molK$^2$ 'plateau' in at least five Yb-based very-heavy-fermions VHF compounds; ii) quantitative and qualitative differences between VHF and standard non-Fermi-liquids. iii) Entropy-bottlenecks governing the change of $S_m(T)$ trajectories in a continuous transition into alternative ground states that exhibits third order characteristics. An empirical analysis of the possible $S_m(T\to 0)$ dependencies according to the $\partial ^2 S_m/\partial T^2$ derivative is also preformed. Altogether, this work can be regarded as an empirical application of the third law of thermodynamics.