Seminar : A new twist on spin nematics/quadrupoles

Title

A new twist on spin nematics/quadrupoles

Speaker　

Mr. Katsuhiro Tanaka - Department of Basic Science, University of Tokyo

March 2016: Bachelor’s degree, Department of Chemistry, School of Science, University of Tokyo
March 2018: Master’s degree, Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo
April 2018–present: Doctoral student in Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo

Abstract

In this talk, we make two proposals on nematic/quadrupolar ordering in quantum spin systems: (1) some hint to detect spin-1 nematics using a magnetic field, and (2) finding rich quadrupolar phases in a spin-1 dimer system by making use of a large internal degrees of freedom. Spin nematics is basically a family of “hidden orderings”, and how to detect them or realize them in material systems had been discussed for years. In the first topic, we discuss the magnetic field effect on the finite-temperature properties of spin-1 bilinear-biquadratic model in 2D, where we observed the field-reentrant phase transition to the ferro-nematic phase [1]. This reentrant behavior is ascribed to the entropic effect originating from the different robustness against a magnetic field between the paramagnetic and ferro-nematic phases. Second topic deals with the spin-1 dimer parallelly aligned forming a 2D layer. We find three types of Heisenberg-interaction-driven quadrupolar phases formed by spin-1 bosons living on a dimerized spin-1 pair [2]. These phases are classified in terms of the internal degrees of freedom of a dimer. In one of them, the p-type vector chiral correlations develop, which may explain the spin-liquild-like behavior observed in the dimer material Ba3ZnRu2O9 [3].

[1] K. Tanaka and C. Hotta, Phys. Rev. B 102, 140401(R) (2020).
[2] K. Tanaka and C. Hotta, Phys. Rev. B 101, 094422 (2020).
[3] I. Terasaki et al., J. Phys. Soc. Jpn. 86, 033702 (2017).