Low temperature pseudo-phase transition in an extended Hubbard diamond chain

TL;DR

This paper investigates a low-temperature pseudo-phase transition in an extended Hubbard diamond chain, revealing sharp peaks in physical quantities and defining pseudo-critical exponents, thus providing insights into transition-like phenomena without true phase change.

Contribution

The study introduces a rigorous analysis of pseudo-transition effects in an extended Hubbard diamond chain, identifying critical exponents and characterizing transition-like behavior in a no-hopping atomic limit.

Findings

Internal energy and entropy show continuous jumps resembling first-order transitions.

Correlation length and specific heat exhibit sharp peaks similar to second-order transitions.

Pseudo-critical exponents are determined as ν=1 and α=3.

Abstract

We consider the extended Hubbard diamond chain with an arbitrary number of particles driven by chemical potential. The interaction between dimer diamond chain and nodal couplings is considered in the atomic limit (no hopping), while the dimer interaction includes the hopping term. We demonstrate that this model exhibits a pseudo-transition effect in the low-temperature regime. Here, we explore the pseudo-transition rigorously by analyzing several physical quantities. The internal energy and entropy depict sudden, although continuous, jumps which closely resembles discontinuous or first-order phase transition. At the same time, the correlation length and specific heat exhibit astonishing strong sharp peaks, quite similar to a second-order phase transition. We associate the ascending and descending part of the peak with power-law \textquotedbl pseudo-critical\textquotedbl exponents. We determine the pseudo-critical exponents in the temperature range where these peaks are developed, namely $\nu=1$ for the correlation length and $\alpha=3$ for the specific heat. We also study the behavior of the electron density and isothermal compressibility around the pseudo-critical temperature.