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arXiv · 2009.05051

Fractionalized fermionic quantum criticality in spin-orbital Mott insulators

Urban F. P. Seifert·Xiao-Yu Dong·Sreejith Chulliparambil·Matthias Vojta·Hong-Hao Tu·Lukas Janssen
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Abstract

We study transitions between topological phases featuring emergent fractionalized excitations in two-dimensional models for Mott insulators with spin and orbital degrees of freedom. The models realize fermionic quantum critical points in fractionalized Gross-Neveu$^\ast$ universality classes in (2+1) dimensions. They are characterized by the same set of critical exponents as their ordinary Gross-Neveu counterparts, but feature a different energy spectrum, reflecting the nontrivial topology of the adjacent phases. We exemplify this in a square-lattice model, for which an exact mapping to a $t$-$V$ model of spinless fermions allows us to make use of large-scale numerical results, as well as in a honeycomb-lattice model, for which we employ $\epsilon$-expansion and large-$N$ methods to estimate the critical behavior. Our results are potentially relevant for Mott insulators with $d^1$ electronic configurations and strong spin-orbit coupling, or for twisted bilayer structures of Kitaev materials.

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Urban F. P. Seifert, Xiao-Yu Dong, Sreejith Chulliparambil, Matthias Vojta, Hong-Hao Tu, Lukas Janssen. 2020-09-10. Fractionalized fermionic quantum criticality in spin-orbital Mott insulators. https://doi.org/10.1103/physrevlett.125.257202

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