Condensed Matter Theory Seminar | September 02, 14:30
Parent Hamiltonians and spin liquid states on the checkerboard and pyrochlore lattices
Parent Hamiltonians---Hamiltonians designed to have interesting states of matter as their ground states---have a long and storied history in Condensed Matter Physics, with examples ranging from the AKLT model to the Haldane pseudopotentials for the Laughlin states. Not only do they provide a "proof of existence" of certain phases but also serve as a controlled starting point for more realistic constructions.
In this talk I will discuss a family of local, SU(2) and time-reversal symmetric Hamiltonians for both spin-1/2 and spin-1 models on the checkerboard and pyrochlore lattices.
For the spin-1/2 case on the checkerboard lattice we find an RVB state which provides an example of a novel mechanism of thermal order by disorder: Instead of the "usual" scenario whereby thermal fluctuations lead to a selection of high-entropy regions of the phase space, in this example a more ordered state emerges via dephasing of quantum interference.
For the spin-1 case, we find an RVB-like state on the 2D checkerboard lattice and a VBS-like state with an emergent U(1) symmetry on the 3D pyrochlore lattice.
This talk is based on two recent preprints, arXiv:2607.12925 and arXiv:2607.15813
UC Riverside
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Contact: Simon Trebst