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dc.contributor.authorGoswami, Pallab
Si, Qimiao
dc.date.accessioned 2017-09-19T18:39:59Z
dc.date.available 2017-09-19T18:39:59Z
dc.date.issued 2017
dc.identifier.citation Goswami, Pallab and Si, Qimiao. "Dynamic zero modes of Dirac fermions and competing singlet phases of antiferromagnetic order." Physical Review B, 95, no. 22 (2017) https://doi.org/10.1103/PhysRevB.95.224438.
dc.identifier.urihttps://hdl.handle.net/1911/97404
dc.description.abstract In quantum spin systems, singlet phases often develop in the vicinity of an antiferromagnetic order. Typical settings for such problems arise when itinerant fermions are also present. In this paper, we develop a theoretical framework for addressing such competing orders in an itinerant system, described by Dirac fermions strongly coupled to an O(3) nonlinear sigma model. We focus on two spatial dimensions, where upon disordering the antiferromagnetic order by quantum fluctuations the singular tunneling events also known as (anti)hedgehogs can nucleate competing singlet orders in the paramagnetic phase. In the presence of an isolated hedgehog configuration of the nonlinear sigma model field, we show that the fermion determinant vanishes as the dynamic Euclidean Dirac operator supports fermion zero modes of definite chirality. This provides a topological mechanism for suppressing the tunneling events. Using the methodology of quantum chromodynamics, we evaluate the fermion determinant in the close proximity of magnetic quantum phase transition, when the antiferromagnetic order-parameter field can be described by a dilute gas of hedgehogs and antihedgehogs. We show how the precise nature of emergent singlet order is determined by the overlap between dynamic fermion zero modes of opposite chirality, localized on the hedgehogs and antihedgehogs. For a Kondo-Heisenberg model on the honeycomb lattice, we demonstrate the competition between spin Peierls order and Kondo singlet formation, thereby elucidating its global phase diagram. We also discuss other physical problems that can be addressed within this general framework.
dc.language.iso eng
dc.rights Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
dc.title Dynamic zero modes of Dirac fermions and competing singlet phases of antiferromagnetic order
dc.type Journal article
dc.citation.journalTitle Physical Review B
dc.citation.volumeNumber 95
dc.citation.issueNumber 22
dc.identifier.digital Dynamic_zero_modes_Dirac_fermions
dc.contributor.publisher American Physical Society
dc.type.dcmi Text
dc.identifier.doihttps://doi.org/10.1103/PhysRevB.95.224438
dc.type.publication publisher version
dc.citation.articleNumber 224438


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