[Seminar] Quantum phase transitions between orthogonal and normal fermions in metals and semi-metals

Speaker

Dr. Snir Gazit - The Hebrew University of Jerusalem

Title

Quantum phase transitions between orthogonal and normal fermions in metals and semi-metals.

Abstract

Orthogonal fermions present the simplest form of electronic fractionalization, where physical (gauge- neutral) electrons split into a local product of spinful fermions and Ising matter fields. This construction naturally gives rise to an emergent Ising gauge structure, which in two space dimensions is potentially topologically ordered. Using sign problem-free quantum Monte Carlo simulations, we investigate a lattice model of orthogonal fermions coupled to Ising gauge fields and matter fields. By tuning microscopic parameters, we control the fractionalization process and establish the resulting phase diagram. In particular, we demonstrate a transition between small and large Fermi surfaces, which crucially does not involve translational symmetry breaking, a phenomenon that violates the conventional Luttinger theorem. Lastly, we uncover a Higgs transition between orthogonal to normal Dirac phases with an emergent U(1) symmetry.

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Meeting ID: 941 0264 0085

For passcode, please contact : megumi.ikeda@oist.jp