Ground-state phase diagram of an anisotropic S=l/2 ladder with alternating rung interactions

TMU International Symposium on "New Quantum Phases Emerging from Novel Crystal Structure"

Tonegawa, Takashi^1,2 ; Okamoto, Kiyomi^3 ; Hikihara, Toshiya^4 ; Sakai, Tôru^5,6

Kobe University, Kobe

657-8501, Japan^1

Department of Physical Science, Osaka Prefecture University, Sakai

599-8531, Japan^2

College of Engineering, Shibaura Institute of Technology, Saitama

337-8570, Japan^3

Faculty of Science and Technology, Gunina University, Kiryu

376-8515, Japan^4

Graduate School of Material Science, University of Hyogo, Hyogo

678-1297, Japan^5

Japan Atomic Energy Agency, SPring-8, Hyogo

679-5148, Japan^6

关键词: Antiferromagnetics;    Ground state phase diagram;    Haldane;    Interaction anisotropy;    Inversion phenomena;    Phase region;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/683/1/012039/pdf
DOI  :  10.1088/1742-6596/683/1/012039

来源: IOP

【 摘 要 】

Employing mainly numerical methods, we explore the ground-state phase diagram of an anisotropic S = 1/2 ladder, in which leg interactions are uniform and isotropic, while rung interactions are alternating and have a common Ising-t.ype anisotropy. We determine the phase diagram in the case where Jleg= 0.2 (antiferromagnetic), Jrung= - 1.0 (ferromagnetic) and |J′rung| ≤ 1.0, the first one being the magnitude of the leg interaction and the second and third ones those of the rung interactions, which are alternating. It is emphasized that the system has a frustration when J'rungis positive. We find that., in the frustrated region, the Haldane state appears as the ground state even when the Ising character of rung interactions is strong. This appearance of the Haldane phase is contrary to the ordinary situation, and it is called the inversion phenomenon concerning the interaction anisotropy. We also find that an incommensurate state becomes the ground state in a portion of the Haldane phase region.