Dynamic zero modes of Dirac fermions and competing singlet phases of antiferromagnetic order
| dc.citation.articleNumber | 224438 | |
| dc.citation.issueNumber | 22 | |
| dc.citation.journalTitle | Physical Review B | |
| dc.citation.volumeNumber | 95 | |
| dc.contributor.author | Goswami, Pallab | |
| dc.contributor.author | Si, Qimiao | |
| dc.date.accessioned | 2017-09-19T18:39:59Z | |
| dc.date.available | 2017-09-19T18:39:59Z | |
| dc.date.issued | 2017 | |
| 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.identifier.citation | Goswami, Pallab and Si, Qimiao. "Dynamic zero modes of Dirac fermions and competing singlet phases of antiferromagnetic order." <i>Physical Review B,</i> 95, no. 22 (2017) American Physical Society: https://doi.org/10.1103/PhysRevB.95.224438. | |
| dc.identifier.digital | Dynamic_zero_modes_Dirac_fermions | |
| dc.identifier.doi | https://doi.org/10.1103/PhysRevB.95.224438 | |
| dc.identifier.uri | https://hdl.handle.net/1911/97404 | |
| dc.language.iso | eng | |
| dc.publisher | American Physical Society | |
| 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.type.dcmi | Text | |
| dc.type.publication | publisher version |
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