Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 104: Topological Insulators II (jointly with MA, DS, HL, O)
TT 104.9: Talk
Thursday, March 19, 2015, 17:00–17:15, EB 202
Classification of spin liquids on the square lattice with strong spin-orbit coupling — •Johannes Reuther1,2, Shu-Ping Lee3, and Jason Alicea3 — 1Freie Universität Berlin — 2Helmholtz-Zentrum Berlin für Materialien und Energie — 3California Institute of Technology
The investigation of spin liquids is a fascinating field in condensed matter physics that is increasingly motivated by experiments. Exhaustive classifications of spin liquids have been carried out in several systems, particularly when full SU(2) spin-rotation symmetry is present. Systematic studies that explore strongly spin-orbit-coupled magnetic compounds (for which there are many experimental examples) are, however, relatively scarce. We report on a classification of Z2 spin liquids on the square lattice when SU(2) spin symmetry is maximally lifted. Using projective symmetry group methods, we find that, surprisingly, the lifting of spin symmetry yields vastly more spin liquid states compared to SU(2)-invariant systems. A generic feature of the SU(2)-broken case is that the spinons naturally undergo p+ip pairing; consequently, many of these Z2 spin liquids feature a topologically nontrivial spinon band structure supporting gapless Majorana edge states. These boundary modes are often protected by a combination of time reversal and lattice symmetries and hence resemble recently proposed topological crystalline superconductors.