Field dependent thermodynamics and Quantum Critical Phenomena in the dimerized spin system Cu2(C5H12N2)2Cl4

TL;DR

This paper investigates the thermodynamic behavior and quantum critical phenomena in the dimerized spin system Cu2(C5H12N2)2Cl4, comparing experimental data with theoretical models to understand its dimensionality and critical behavior.

Contribution

It demonstrates that Cu2(C5H12N2)2Cl4's thermodynamics are largely insensitive to the coupling details due to weakly coupled dimers and explores quantum critical scaling near the critical field.

Findings

Thermodynamic data align with models of weakly coupled dimers.

Quantum critical behavior exhibits power-law temperature dependence.

Dimensionality effects are observable in thermodynamic scaling.

Abstract

Experimental data for the uniform susceptibility, magnetization and specific heat for the material Cu2(C5H12N2)2Cl4 (abbreviated CuHpCl) as a function of temperature and external field are compared with those of three different dimerized spin models: alternating spin-chains, spin-ladders and the bilayer Heisenberg model. It is shown that because this material consists of weakly coupled spin-dimers, much of the data is insensitive to how the dimers are coupled together and what the effective dimensionality of the system is. When such a system is tuned to the quantum critical point by application of a field, the dimensionality shows up in the power-law dependences of thermodynamic quantities on temperature. We discuss the temperature window for such a quantum critical behavior in CuHpCl.