Multiple topological phases in phononic crystals

Handle URI:
http://hdl.handle.net/10754/626738
Title:
Multiple topological phases in phononic crystals
Authors:
Chen, Zeguo ( 0000-0002-2910-8264 ) ; Wu, Ying ( 0000-0002-7919-1107 )
Abstract:
We report a new topological phononic crystal in a ring-waveguide acoustic system. In the previous reports on topological phononic crystals, there are two types of topological phases: quantum Hall phase and quantum spin Hall phase. A key point in achieving quantum Hall insulator is to break the time-reversal (TR) symmetry, and for quantum spin Hall insulator, the construction of pseudo-spin is necessary. We build such pseudo-spin states under particular crystalline symmetry (C-6v) and then break the degeneracy of the pseudo-spin states by introducing airflow to the ring. We study the topology evolution by changing both the geometric parameters of the unit cell and the strength of the applied airflow. We find that the system exhibits three phases: quantum spin Hall phase, conventional insulator phase and a new quantum anomalous Hall phase.; The quantum anomalous Hall phase is first observed in phononics and cannot be simply classified by the Chern number or Z(2) index since it results from TR-broken quantum spin Hall phase. We develop a tight-binding model to capture the essential physics of the topological phase transition. The analytical calculation based on the tight-binding model shows that the spin Chern number is a topological invariant to classify the bandgap. The quantum anomalous Hall insulator has a spin Chern number C-+/- = (1; 0) indicating the edge state is pseudo-spin orientation dependent and robust against TR-broken impurities.; We also perform finite-element numerical simulations to verify the topological differences of the bandgaps. At the interface between a conventional insulator and a quantum anomalous Hall insulator, pseudo-spin dependent one-way propagation interface states are clearly observed, which are strikingly deferent from chiral edge states resulting from quantum Hall insulator and pairs of helical edge states resulting from quantum spin Hall insulator. Moreover, our pseudo-spin dependent edge state is robust against TR-broken impurities, which also sheds lights on spintronic devices.
KAUST Department:
Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division; Applied Mathematics and Computational Science Program
Publisher:
Chinese Physical Society
Journal:
ACTA PHYSICA SINICA
KAUST Grant Number:
BAS/1/1626-01-01
Issue Date:
20-Nov-2017
DOI:
10.7498/aps.66.227804
Type:
Article
ISSN:
1000-3290
Sponsors:
Project supported by King Abdullah University of Science and Technology Baseline Research Fund (Grant No. BAS/1/1626-01-01).
Additional Links:
http://wulixb.iphy.ac.cn/CN/10.7498/aps.66.227804
Appears in Collections:
Articles; Applied Mathematics and Computational Science Program; Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorChen, Zeguoen
dc.contributor.authorWu, Yingen
dc.date.accessioned2018-01-11T08:25:51Z-
dc.date.available2018-01-11T08:25:51Z-
dc.date.issued2017-11-20en
dc.identifier.issn1000-3290en
dc.identifier.doi10.7498/aps.66.227804en
dc.identifier.urihttp://hdl.handle.net/10754/626738-
dc.description.abstractWe report a new topological phononic crystal in a ring-waveguide acoustic system. In the previous reports on topological phononic crystals, there are two types of topological phases: quantum Hall phase and quantum spin Hall phase. A key point in achieving quantum Hall insulator is to break the time-reversal (TR) symmetry, and for quantum spin Hall insulator, the construction of pseudo-spin is necessary. We build such pseudo-spin states under particular crystalline symmetry (C-6v) and then break the degeneracy of the pseudo-spin states by introducing airflow to the ring. We study the topology evolution by changing both the geometric parameters of the unit cell and the strength of the applied airflow. We find that the system exhibits three phases: quantum spin Hall phase, conventional insulator phase and a new quantum anomalous Hall phase.en
dc.description.abstractThe quantum anomalous Hall phase is first observed in phononics and cannot be simply classified by the Chern number or Z(2) index since it results from TR-broken quantum spin Hall phase. We develop a tight-binding model to capture the essential physics of the topological phase transition. The analytical calculation based on the tight-binding model shows that the spin Chern number is a topological invariant to classify the bandgap. The quantum anomalous Hall insulator has a spin Chern number C-+/- = (1; 0) indicating the edge state is pseudo-spin orientation dependent and robust against TR-broken impurities.en
dc.description.abstractWe also perform finite-element numerical simulations to verify the topological differences of the bandgaps. At the interface between a conventional insulator and a quantum anomalous Hall insulator, pseudo-spin dependent one-way propagation interface states are clearly observed, which are strikingly deferent from chiral edge states resulting from quantum Hall insulator and pairs of helical edge states resulting from quantum spin Hall insulator. Moreover, our pseudo-spin dependent edge state is robust against TR-broken impurities, which also sheds lights on spintronic devices.en
dc.description.sponsorshipProject supported by King Abdullah University of Science and Technology Baseline Research Fund (Grant No. BAS/1/1626-01-01).en
dc.language.isocn-
dc.publisherChinese Physical Societyen
dc.relation.urlhttp://wulixb.iphy.ac.cn/CN/10.7498/aps.66.227804en
dc.rightsArchived with thanks to Acta Physica Sinicaen
dc.subjectphononic crystalen
dc.subjecttopologyen
dc.subjectquantum anomalous Hall effecten
dc.titleMultiple topological phases in phononic crystalsen
dc.typeArticleen
dc.contributor.departmentComputer, Electrical and Mathematical Sciences and Engineering (CEMSE) Divisionen
dc.contributor.departmentApplied Mathematics and Computational Science Programen
dc.identifier.journalACTA PHYSICA SINICAen
dc.eprint.versionPost-printen
kaust.authorChen, Zeguoen
kaust.authorWu, Yingen
kaust.grant.numberBAS/1/1626-01-01en
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