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Exploring the Quantum Phase Transition of Strongly Correlated Massless Dirac Fermions

Akito Kobayashi

Published Jan 15, 2021• 2 citations
Publisher

Abstract

Researchers have shown that a massless Dirac fermion system exhibits a quantum phase transition in the presence of strong electronic correlations.
DOI
10.7566/jpsjnc.18.02

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In a two-dimensional electron gas under a strong magnetic field, correlations generate emergent excitations distinct from electrons. It has been predicted that "composite fermions"--bound states of an electron with two magnetic flux quanta--can experience zero net magnetic field and form a Fermi sea. Using infinite-cylinder density matrix renormalization group numerical simulations, we verify the existence of this exotic Fermi sea, but find that the phase exhibits particle-hole symmetry. This is self-consistent only if composite fermions are massless Dirac particles, similar to the surface of a topological insulator. Exploiting this analogy, we observe the suppression of 2k(F) backscattering, a characteristic of Dirac particles. Thus, the phenomenology of Dirac fermions is also relevant to two-dimensional electron gases in the quantum Hall regime.
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