期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2019
卷号：116
期号：25
页码：12199-12203
DOI：10.1073/pnas.1821406116
出版社：The National Academy of Sciences of the United States of America
摘要：The Kitaev model with an applied magnetic field in the H ∥ [ 111 ] direction shows two transitions: from a nonabelian gapped quantum spin liquid (QSL) to a gapless QSL at H c 1 ≃ 0.2 K and a second transition at a higher field H c 2 ≃ 0.35 K to a gapped partially polarized phase, where K is the strength of the Kitaev exchange interaction. We identify the intermediate phase to be a gapless U(1) QSL and determine the spin structure function S ( k ) and the Fermi surface ϵ F S ( k ) of the gapless spinons using the density matrix renormalization group (DMRG) method for large honeycomb clusters. Further calculations of static spin-spin correlations, magnetization, spin susceptibility, and finite temperature-specific heat and entropy corroborate the gapped and gapless nature of the different field-dependent phases. In the intermediate phase, the spin-spin correlations decay as a power law with distance, indicative of a gapless phase.
关键词：quantum spin liquid ; fractionalization ; Kitaev model ; spinon
