Guoxin Zheng, Dechen Zhang, Yuan Zhu, Kuan-Wen Chen, Aaron Chan, Kaila Jenkins, Byungmin Kang, Zhenyuan Zeng, Aini Xu, D. Ratkovski, Joanna Blawat, Alimamy F. Bangura, John Singleton, Patrick A. Lee, Shiliang Li, Lu Li
{"title":"Thermodynamic Evidence of Fermionic Behavior in the Vicinity of One-Ninth Plateau in a Kagome Antiferromagnet","authors":"Guoxin Zheng, Dechen Zhang, Yuan Zhu, Kuan-Wen Chen, Aaron Chan, Kaila Jenkins, Byungmin Kang, Zhenyuan Zeng, Aini Xu, D. Ratkovski, Joanna Blawat, Alimamy F. Bangura, John Singleton, Patrick A. Lee, Shiliang Li, Lu Li","doi":"10.1103/physrevx.15.021076","DOIUrl":null,"url":null,"abstract":"The spin-1</a:mn>/</a:mo>2</a:mn></a:mrow></a:math> kagome Heisenberg antiferromagnets are believed to host exotic quantum entangled states. Recently, the reports of <c:math xmlns:c=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><c:mrow><c:mn>1</c:mn><c:mo>/</c:mo><c:mn>9</c:mn></c:mrow></c:math> magnetization plateau and magnetic oscillations in a kagome antiferromagnet <e:math xmlns:e=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><e:mrow><e:mrow><e:msub><e:mrow><e:mi>YCu</e:mi></e:mrow><e:mrow><e:mn>3</e:mn></e:mrow></e:msub></e:mrow><e:msub><e:mrow><e:mo stretchy=\"false\">(</e:mo><e:mrow><e:mi>OH</e:mi></e:mrow><e:mo stretchy=\"false\">)</e:mo></e:mrow><e:mrow><e:mn>6</e:mn></e:mrow></e:msub><e:mrow><e:msub><e:mrow><e:mi>Br</e:mi></e:mrow><e:mrow><e:mn>2</e:mn></e:mrow></e:msub></e:mrow><e:mo stretchy=\"false\">[</e:mo><e:msub><e:mrow><e:mtext>Br</e:mtext></e:mrow><e:mrow><e:mi>x</e:mi></e:mrow></e:msub><e:msub><e:mrow><e:mo stretchy=\"false\">(</e:mo><e:mrow><e:mi>OH</e:mi></e:mrow><e:mo stretchy=\"false\">)</e:mo></e:mrow><e:mrow><e:mn>1</e:mn><e:mo>−</e:mo><e:mi>x</e:mi></e:mrow></e:msub><e:mo stretchy=\"false\">]</e:mo></e:mrow></e:math> (YCOB) have made this material a promising candidate for experimentally realizing quantum spin liquid states. Here, we present measurements of the specific heat <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><m:msub><m:mi>C</m:mi><m:mi>p</m:mi></m:msub></m:math> in YCOB in high magnetic fields (up to 41.5 T) down to 0.46 K, and the <o:math xmlns:o=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><o:mrow><o:mn>1</o:mn><o:mo>/</o:mo><o:mn>9</o:mn></o:mrow></o:math> plateau feature has been confirmed. Moreover, the temperature dependence of <q:math xmlns:q=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><q:msub><q:mi>C</q:mi><q:mi>p</q:mi></q:msub><q:mo>/</q:mo><q:mi>T</q:mi></q:math> in the vicinity of <s:math xmlns:s=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><s:mrow><s:mn>1</s:mn><s:mo>/</s:mo><s:mn>9</s:mn></s:mrow></s:math> plateau region can be fitted by a linear in <u:math xmlns:u=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><u:mi>T</u:mi></u:math> term which indicates the presence of a Dirac spectrum, together with a constant term, which indicates a finite density of states contributed by other spinon Fermi surfaces. Surprisingly, the constant term is highly anisotropic in the direction of the magnetic field. Additionally, we observe a double-peak feature near 30 T above the <w:math xmlns:w=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><w:mrow><w:mn>1</w:mn><w:mo>/</w:mo><w:mn>9</w:mn></w:mrow></w:math> plateau which is another hallmark of fermionic excitations in the specific heat. This combination of gapless behavior and the double-peak structure strongly suggests that the <y:math xmlns:y=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><y:mrow><y:mn>1</y:mn><y:mo>/</y:mo><y:mn>9</y:mn></y:mrow></y:math> plateau in YCOB is nontrivial and hosts fermionic quasiparticles. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20161,"journal":{"name":"Physical Review X","volume":"11 1","pages":""},"PeriodicalIF":15.7000,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physical Review X","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1103/physrevx.15.021076","RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"PHYSICS, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The spin-1/2 kagome Heisenberg antiferromagnets are believed to host exotic quantum entangled states. Recently, the reports of 1/9 magnetization plateau and magnetic oscillations in a kagome antiferromagnet YCu3(OH)6Br2[Brx(OH)1−x] (YCOB) have made this material a promising candidate for experimentally realizing quantum spin liquid states. Here, we present measurements of the specific heat Cp in YCOB in high magnetic fields (up to 41.5 T) down to 0.46 K, and the 1/9 plateau feature has been confirmed. Moreover, the temperature dependence of Cp/T in the vicinity of 1/9 plateau region can be fitted by a linear in T term which indicates the presence of a Dirac spectrum, together with a constant term, which indicates a finite density of states contributed by other spinon Fermi surfaces. Surprisingly, the constant term is highly anisotropic in the direction of the magnetic field. Additionally, we observe a double-peak feature near 30 T above the 1/9 plateau which is another hallmark of fermionic excitations in the specific heat. This combination of gapless behavior and the double-peak structure strongly suggests that the 1/9 plateau in YCOB is nontrivial and hosts fermionic quasiparticles. Published by the American Physical Society2025
期刊介绍:
Physical Review X (PRX) stands as an exclusively online, fully open-access journal, emphasizing innovation, quality, and enduring impact in the scientific content it disseminates. Devoted to showcasing a curated selection of papers from pure, applied, and interdisciplinary physics, PRX aims to feature work with the potential to shape current and future research while leaving a lasting and profound impact in their respective fields. Encompassing the entire spectrum of physics subject areas, PRX places a special focus on groundbreaking interdisciplinary research with broad-reaching influence.