Vacancy-Induced Low-Energy Density of States in the Kitaev Spin Liquid

The Kitaev honeycomb model has attracted significant attention due to its exactly solvable spin-liquid ground state with fractionalized Majorana excitations and its possible materialization in magnetic Mott insulators with strong spin-orbit couplings. Recently, the 5d-electron compound H_{3}LiIr_{2}...

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Autores principales:	Wen-Han Kao, Johannes Knolle, Gábor B. Halász, Roderich Moessner, Natalia B. Perkins
Formato:	article
Lenguaje:	EN
Publicado:	American Physical Society 2021
Materias:	Physics QC1-999
Acceso en línea:	https://doaj.org/article/9ee49d897ada43b7a1f9da57f47e1d60
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spelling	oai:doaj.org-article:9ee49d897ada43b7a1f9da57f47e1d602021-12-02T10:53:15ZVacancy-Induced Low-Energy Density of States in the Kitaev Spin Liquid10.1103/PhysRevX.11.0110342160-3308https://doaj.org/article/9ee49d897ada43b7a1f9da57f47e1d602021-02-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.11.011034http://doi.org/10.1103/PhysRevX.11.011034https://doaj.org/toc/2160-3308The Kitaev honeycomb model has attracted significant attention due to its exactly solvable spin-liquid ground state with fractionalized Majorana excitations and its possible materialization in magnetic Mott insulators with strong spin-orbit couplings. Recently, the 5d-electron compound H_{3}LiIr_{2}O_{6} has shown to be a strong candidate for Kitaev physics considering the absence of any signs of a long-range ordered magnetic state. In this work, we demonstrate that a finite density of random vacancies in the Kitaev model gives rise to a striking pileup of low-energy Majorana eigenmodes and reproduces the apparent power-law upturn in the specific heat measurements of H_{3}LiIr_{2}O_{6}. Physically, the vacancies can originate from various sources such as missing magnetic moments or the presence of nonmagnetic impurities (true vacancies), or from local weak couplings of magnetic moments due to strong but rare bond randomness (quasivacancies). We show numerically that the vacancy effect is readily detectable even at low vacancy concentrations and that it is not very sensitive either to the nature of vacancies or to different flux backgrounds. We also study the response of the site-diluted Kitaev spin liquid to the three-spin interaction term, which breaks time-reversal symmetry and imitates an external magnetic field. We propose a field-induced flux-sector transition where the ground state becomes flux-free for larger fields, resulting in a clear suppression of the low-temperature specific heat. Finally, we discuss the effect of dangling Majorana fermions in the case of true vacancies and show that their coupling to an applied magnetic field via the Zeeman interaction can also account for the scaling behavior in the high-field limit observed in H_{3}LiIr_{2}O_{6}.Wen-Han KaoJohannes KnolleGábor B. HalászRoderich MoessnerNatalia B. PerkinsAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 11, Iss 1, p 011034 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999
spellingShingle	Physics QC1-999 Wen-Han Kao Johannes Knolle Gábor B. Halász Roderich Moessner Natalia B. Perkins Vacancy-Induced Low-Energy Density of States in the Kitaev Spin Liquid
description	The Kitaev honeycomb model has attracted significant attention due to its exactly solvable spin-liquid ground state with fractionalized Majorana excitations and its possible materialization in magnetic Mott insulators with strong spin-orbit couplings. Recently, the 5d-electron compound H_{3}LiIr_{2}O_{6} has shown to be a strong candidate for Kitaev physics considering the absence of any signs of a long-range ordered magnetic state. In this work, we demonstrate that a finite density of random vacancies in the Kitaev model gives rise to a striking pileup of low-energy Majorana eigenmodes and reproduces the apparent power-law upturn in the specific heat measurements of H_{3}LiIr_{2}O_{6}. Physically, the vacancies can originate from various sources such as missing magnetic moments or the presence of nonmagnetic impurities (true vacancies), or from local weak couplings of magnetic moments due to strong but rare bond randomness (quasivacancies). We show numerically that the vacancy effect is readily detectable even at low vacancy concentrations and that it is not very sensitive either to the nature of vacancies or to different flux backgrounds. We also study the response of the site-diluted Kitaev spin liquid to the three-spin interaction term, which breaks time-reversal symmetry and imitates an external magnetic field. We propose a field-induced flux-sector transition where the ground state becomes flux-free for larger fields, resulting in a clear suppression of the low-temperature specific heat. Finally, we discuss the effect of dangling Majorana fermions in the case of true vacancies and show that their coupling to an applied magnetic field via the Zeeman interaction can also account for the scaling behavior in the high-field limit observed in H_{3}LiIr_{2}O_{6}.
format	article
author	Wen-Han Kao Johannes Knolle Gábor B. Halász Roderich Moessner Natalia B. Perkins
author_facet	Wen-Han Kao Johannes Knolle Gábor B. Halász Roderich Moessner Natalia B. Perkins
author_sort	Wen-Han Kao
title	Vacancy-Induced Low-Energy Density of States in the Kitaev Spin Liquid
title_short	Vacancy-Induced Low-Energy Density of States in the Kitaev Spin Liquid
title_full	Vacancy-Induced Low-Energy Density of States in the Kitaev Spin Liquid
title_fullStr	Vacancy-Induced Low-Energy Density of States in the Kitaev Spin Liquid
title_full_unstemmed	Vacancy-Induced Low-Energy Density of States in the Kitaev Spin Liquid
title_sort	vacancy-induced low-energy density of states in the kitaev spin liquid
publisher	American Physical Society
publishDate	2021
url	https://doaj.org/article/9ee49d897ada43b7a1f9da57f47e1d60
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Vacancy-Induced Low-Energy Density of States in the Kitaev Spin Liquid

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