Electron correlation effects and spin-liquid state in the Herbertsmithite Kagome lattice

TL;DR

This study uses advanced quantum Monte Carlo methods to analyze electron correlations in the Kagome lattice of Herbertsmithite, revealing the emergence of a quantum spin liquid state driven by long-range correlations.

Contribution

It introduces a comprehensive variational approach with multiple trial wave functions to explore correlation effects and spin-liquid behavior in the Kagome lattice system.

Findings

Correlation energy increases with Zn concentration.

Optimizing the Slater determinant significantly enhances correlation energy.

Evidence suggests a quantum spin liquid state driven by long-range correlations.

Abstract

We employ real-space variational quantum Monte Carlo methods with resonating valence bond many-body wave functions to investigate electron correlation effects in the Kagome system $Zn_xCu_{4-x}O_6$. Using three trial wave functions of the Slater-Jastrow type, where (i) only the Jastrow correlation factor is optimized and the orbitals obtained by density functional theory, (ii) both the Jastrow factor and the Slater determinant are optimized, and (iii) additionally the Slater determinant is substituted by an antisymmetrized-geminal power wave function, we analyze static and dynamic correlation energies across concentrations $x=0, \frac{1}{3}, \frac{2}{3}, 1$. Our results show that the correlation energy increases with the concentration of $Zn_x$. Optimizing the Slater determinant significantly enhances the correlation energy by approximately $\sim -73(4) mHa$ per electron. Eventually, the emergence of a quantum spin liquid state driven by a long-range correlation energy is discussed.