Thermodynamics of Spin-1/2 Kagom\'e Heisenberg Antiferromagnet: Algebraic Paramagnetic Liquid and Finite-Temperature Phase Diagram

TL;DR

This paper investigates how thermal fluctuations influence the quantum spin liquid state in the spin-1/2 kagome Heisenberg antiferromagnet, revealing an algebraic paramagnetic liquid and mapping its finite-temperature phase diagram.

Contribution

It introduces the concept of an algebraic paramagnetic liquid and provides a detailed finite-temperature phase diagram for the kagome antiferromagnet using tensor network methods.

Findings

Ground state consistent with a gapless quantum spin liquid

Identification of an algebraic paramagnetic liquid phase

Finite-temperature phase diagram with multiple phases

Abstract

Quantum fluctuations from frustration can trigger quantum spin liquids (QSLs) at zero temperature. However, it is unclear how thermal fluctuations affect a QSL. We employ state-of-the-art tensor network-based methods to explore the ground state and thermodynamic properties of the spin-1/2 kagome Heisenberg antiferromagnet (KHA). Its ground state is shown to be consistent with a gapless QSL by observing the absence of zero-magnetization plateau as well as the algebraic behaviors of susceptibility and specific heat at low temperatures, respectively. We show that there exists an \textit{algebraic paramagnetic liquid} (APL) that possesses both the paramagnetic properties and the algebraic behaviors inherited from the QSL. The APL is induced under the interplay between quantum fluctuations from geometrical frustration and thermal fluctuations. By studying the temperature-dependent behaviors of specific heat and magnetic susceptibility, a finite-temperature phase diagram in a magnetic field is suggested, where various phases are identified. This present study gains useful insight into the thermodynamic properties of the spin-1/2 KHA with or without a magnetic field and is helpful for relevant experimental studies.