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postgraduate thesis: Boltzmann equation and semiclassical magnetoconductivity in Weyl semimetal
Title  Boltzmann equation and semiclassical magnetoconductivity in Weyl semimetal 

Authors  
Issue Date  2016 
Publisher  The University of Hong Kong (Pokfulam, Hong Kong) 
Citation  Wu, H. [吴昊]. (2016). Boltzmann equation and semiclassical magnetoconductivity in Weyl semimetal. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. 
Abstract  Weyl semimetal is a kind of threedimensional material which has several band touch points in the energy band structure. These band touch points are called Weyl nodes, which are associated with a quantity called chirality. Near each Weyl node, the behaviour of electrons can be described by Weyl equation. Weyl nodes can be regarded as monopoles in momentum space with charges ±1. Due to the fermion doubling theorem, each Weyl node should be paired with another node with opposite chirality. For a single Weyl node, the number of charges is no longer conserved in the presence of paralleled electric and magnetic field. This phenomenon is called chiral anomaly. Chiral anomaly will lead to some novel transport phenomena such as negative magnetoresistance and chiral magnetic effect. Weyl semimetal also has novel surface states which are called Fermi arcs. TaAs is the first kind of Weyl semimetal material which is discovered in experiments. Fermi arcs and negative magnetoresistance have been observed in TaAs. This work focuses on magnetoresistance of Weyl semimetal systems. In contrast with quantum limit, we consider the case which Boltzmann equation can be used in calculation. To solve the Boltzmann equation, we use the relaxation time approximation to deal with the collision term. Then the collision term is divided into two parts, which describe both intra and internode scattering respectively. With the solution of Boltzmann equation, we can get the analytical expression of the conductivity. Modifications of orbital magnetic moment and classical cyclotron motion term are considered in this work. This calculation gives a longitudinal conductivity which is proportional to B^2, which is coincided with previous theories. 
Degree  Master of Philosophy 
Subject  Condensed matter 
Dept/Program  Physics 
Persistent Identifier  http://hdl.handle.net/10722/235927 
HKU Library Item ID  b5801696 
DC Field  Value  Language 

dc.contributor.author  Wu, Hao   
dc.contributor.author  吴昊   
dc.date.accessioned  20161109T23:27:04Z   
dc.date.available  20161109T23:27:04Z   
dc.date.issued  2016   
dc.identifier.citation  Wu, H. [吴昊]. (2016). Boltzmann equation and semiclassical magnetoconductivity in Weyl semimetal. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR.   
dc.identifier.uri  http://hdl.handle.net/10722/235927   
dc.description.abstract  Weyl semimetal is a kind of threedimensional material which has several band touch points in the energy band structure. These band touch points are called Weyl nodes, which are associated with a quantity called chirality. Near each Weyl node, the behaviour of electrons can be described by Weyl equation. Weyl nodes can be regarded as monopoles in momentum space with charges ±1. Due to the fermion doubling theorem, each Weyl node should be paired with another node with opposite chirality. For a single Weyl node, the number of charges is no longer conserved in the presence of paralleled electric and magnetic field. This phenomenon is called chiral anomaly. Chiral anomaly will lead to some novel transport phenomena such as negative magnetoresistance and chiral magnetic effect. Weyl semimetal also has novel surface states which are called Fermi arcs. TaAs is the first kind of Weyl semimetal material which is discovered in experiments. Fermi arcs and negative magnetoresistance have been observed in TaAs. This work focuses on magnetoresistance of Weyl semimetal systems. In contrast with quantum limit, we consider the case which Boltzmann equation can be used in calculation. To solve the Boltzmann equation, we use the relaxation time approximation to deal with the collision term. Then the collision term is divided into two parts, which describe both intra and internode scattering respectively. With the solution of Boltzmann equation, we can get the analytical expression of the conductivity. Modifications of orbital magnetic moment and classical cyclotron motion term are considered in this work. This calculation gives a longitudinal conductivity which is proportional to B^2, which is coincided with previous theories.   
dc.language  eng   
dc.publisher  The University of Hong Kong (Pokfulam, Hong Kong)   
dc.relation.ispartof  HKU Theses Online (HKUTO)   
dc.rights  The author retains all proprietary rights, (such as patent rights) and the right to use in future works.   
dc.rights  This work is licensed under a Creative Commons AttributionNonCommercialNoDerivatives 4.0 International License.   
dc.subject.lcsh  Condensed matter   
dc.title  Boltzmann equation and semiclassical magnetoconductivity in Weyl semimetal   
dc.type  PG_Thesis   
dc.identifier.hkul  b5801696   
dc.description.thesisname  Master of Philosophy   
dc.description.thesislevel  Master   
dc.description.thesisdiscipline  Physics   
dc.description.nature  published_or_final_version   