1. Condensed-Matter Physics & Materials Science Seminar

    "Z2 spin liquid in S=1/2 kagome Heisenberg antiferromagnet"

    Presented by Yuan Wan, Department of Physics and Astronomy Johns Hopkins University

    Thursday, January 23, 2014, 1:30 pm
    Bldg. 734, ISB Conf. Rm. 201 (upstairs)

    Hosted by: Alexei Tsvelik/Robert Konik

    A quantum spin liquid is a hypothesized ground state of a magnet without long-range magnetic order. Similar to a liquid, which is spatially uniform and strongly correlated, a quantum spin liquid preserves all the symmetries and exhibits strong correlations between spins. First proposed by P. W. Anderson in 1973, it has remained a conjecture until recently. In the past couple of years, numerical studies have provided strong evidences for quantum spin liquid in a simple model, the kagome Heisenberg antiferromagnet. In this talk, I will describe a low-energy effective theory for this magnet in terms of a lattice gauge theory with the simplest possible mathematical structure (a group of two elements, namely Z2). I will show that the theory reproduces many characteristic features observed numerically, thereby providing a bridge between the numeircs and the analytics. Furthermore, I will present theoretical predictions which could be tested in future numerical studies.