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Landau-like states in neutral particles
KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Los Alamos Natl Lab, USA.
KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.ORCID-id: 0000-0002-1763-9383
KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
2016 (engelsk)Inngår i: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 93, nr 23, artikkel-id 235134Artikkel i tidsskrift (Fagfellevurdert) Published
Resurstyp
Text
Abstract [en]

We show the emergence of a new type of dispersion relation for neutral atoms with an interesting similarity to the spectrum of two-dimensional electrons in an applied perpendicular constant magnetic field. These neutral atoms can be confined in toroidal optical traps and give quasi-Landau spectra. In strong contrast to the equidistant infinitely degenerate Landau levels for charged particles, the spectral gap for such two-dimensional neutral particles increases in particular electric-field configurations. The idea in the paper is motivated by the development in cold atom experiments and builds on the seminal paper of Aharonov and Casher.

sted, utgiver, år, opplag, sider
2016. Vol. 93, nr 23, artikkel-id 235134
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-189803DOI: 10.1103/PhysRevB.93.235134ISI: 000378105400001Scopus ID: 2-s2.0-84976587185OAI: oai:DiVA.org:kth-189803DiVA, id: diva2:949511
Forskningsfinansiär
EU, European Research Council, DM 321031Swedish Research Council, 2012-3447Knut and Alice Wallenberg Foundation, KAW-2013.0020
Merknad

QC 20160720

Tilgjengelig fra: 2016-07-20 Laget: 2016-07-15 Sist oppdatert: 2018-05-16bibliografisk kontrollert
Inngår i avhandling
1. Interacting Dirac Matter
Åpne denne publikasjonen i ny fane eller vindu >>Interacting Dirac Matter
2018 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The discovery of graphene in 2004 has led to a surge of activities focused on the theoretical and experimental studies of materials hosting linearly dispersive quasiparticles during the last decade. Rapid expansion in the list of materials having similar properties to graphene has led to the emergence of a new class of materials known as the Dirac materials. The low energy quasiparticles in this class of materials are described by a Dirac-like equation in contrast to the Schrödinger equation which governs the low energy dynamics in any conventional materials such as metals. The Dirac fermions, as we call these low-energy quasiparticles, in a wide range of materials ranging from the d-wave superconductors, graphene to the surface states of topological insulators share the common property. The particles move around as if they have lost their mass. This feature results in a completely new set of physical effects consisting of various transport and thermodynamic quantities, that are absent in conventional metals.

This thesis is devoted to studying the properties of bosonic analogs of the commonly known Dirac materials where the quasiparticle are fermionic. In chapter one, we discuss the microscopic origin of the Dirac equation in several fermionic and bosonic systems. We observe identical features of the Dirac materials with quasiparticles of either statistics when the interparticle interaction is absent. Dirac materials with both types of quasiparticles possess the nodal excitations that are described by an effective Dirac-like equation. The possible physical effects due to the linear dispersions in fermionic and bosonic Dirac materials are also outlined.

In chapter two, we propose a system of superconducting grains arranged in honeycomb lattice as a realization for Bosonic Dirac Materials (BDM). The underlying microscopic dynamics, which give rise to the emergence of Dirac structure in the spectrum of the collective phase oscillations, is discussed in detail. Similarities and differences of BDM systems to the conventional Dirac materials with fermionic quasiparticles are also mentioned. Chapter three is dedicated to the detailed analysis of the interaction effects on the stability and renormalization of the conical Dirac band structure. We find that the type of interaction dictates the possible fate of renormalized Dirac cone in both fermionic and bosonic Dirac materials. We study interaction effects in four different individual systems : (a) Dirac fermions in graphene interacting via Coulomb interactions, (b) Dirac fermions subjected to an onsite Hubbard repulsion, (c) Coulomb repulsion in charged Cooper pairs in honeycomb lattice and (d) Dirac magnons interacting via Heisenberg exchange interaction. The possibility of interaction induced gap opening at the Dirac nodal point described is also discussed in these cases.

Chapter four mainly concerns the study of a related topic of the synthetic gauge fields. We discuss the possibility of Landau quantization in neutral particles. Possible experimental evidence in toroidal cold atomic traps is also mentioned. A connection to Landau levels in case of magnons is also described. We finally conclude our thesis in chapter five and discuss the possible future directions that can be taken as an extension for our works in interacting Dirac materials.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2018. s. 102
Serie
TRITA-SCI-FOU ; 2018:22
Emneord
Dirac, superconductor, magnon, interaction, Fermi liquid theory, renormalization
HSV kategori
Forskningsprogram
Fysik
Identifikatorer
urn:nbn:se:kth:diva-227997 (URN)978-91-7729-821-2 (ISBN)
Disputas
2018-06-13, A3: 1077, Roslagstullsbacken 21, Main Building, Floor 3, AlbaNova, Stockholm-106 91, Stockholm, 13:00 (engelsk)
Opponent
Veileder
Merknad

QC 20180516

This thesis contains all the works performed during my doctoral study in physics at Nordita, Sweden.

Tilgjengelig fra: 2018-05-16 Laget: 2018-05-16 Sist oppdatert: 2018-06-19bibliografisk kontrollert

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