Quantum Transport in Topological Phases of Matter

Quantum Transport in Topological Phases of Matter PDF Author: Michal Papaj
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

Get Book Here

Book Description
Topological phases of matter attract constant attention in the condensed matter physics community, both due to the fundamental yet simple principles that govern them, and a multitude of experimental observations with the potential for technological applications. Among the ways of studying such materials, quantum transport methods prove to be of particular importance. In this thesis, I touch upon many aspects of quantum transport in topological materials. First, I introduce a novel type of Hall effect, called Magnus Hall effect, that allows one to probe Berry curvature in ballistic, time-reversal invariant systems that break inversion symmetry. Next, I present a detailed characterization of extrinsic Nernst effect in Dirac and Weyl semimetals, providing interpretation of existing experimental results and predictions for new enhanced responses in materials such as Fe3Sn2. In the following section, I demonstrate that a strong disorder can lead to a novel behavior of Dirac fermions in surface states of topological crystalline insulators, resulting in appearance of nodal arcs in place of Dirac points and in tilting of the Dirac cone. In the second part of the thesis, I focus on topological superconductors, starting by presenting a new method for creating Majorana zero modes using segmented Fermi surface. This approach, based on the Fermi surface of Bogoliubov quasiparticles allows for the reduction of the magnetic field required to induce a topological phase transition and reduces the number of spurious, low energy modes that hamper observation and utilization of Majorana zero modes. Finally, I show that the presence of multiple Majorana modes in a strongly correlated superconducting island leads to Kondo-like behavior with a topological twist.

Quantum Transport in Topological Phases of Matter

Quantum Transport in Topological Phases of Matter PDF Author: Michal Papaj
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

Get Book Here

Book Description
Topological phases of matter attract constant attention in the condensed matter physics community, both due to the fundamental yet simple principles that govern them, and a multitude of experimental observations with the potential for technological applications. Among the ways of studying such materials, quantum transport methods prove to be of particular importance. In this thesis, I touch upon many aspects of quantum transport in topological materials. First, I introduce a novel type of Hall effect, called Magnus Hall effect, that allows one to probe Berry curvature in ballistic, time-reversal invariant systems that break inversion symmetry. Next, I present a detailed characterization of extrinsic Nernst effect in Dirac and Weyl semimetals, providing interpretation of existing experimental results and predictions for new enhanced responses in materials such as Fe3Sn2. In the following section, I demonstrate that a strong disorder can lead to a novel behavior of Dirac fermions in surface states of topological crystalline insulators, resulting in appearance of nodal arcs in place of Dirac points and in tilting of the Dirac cone. In the second part of the thesis, I focus on topological superconductors, starting by presenting a new method for creating Majorana zero modes using segmented Fermi surface. This approach, based on the Fermi surface of Bogoliubov quasiparticles allows for the reduction of the magnetic field required to induce a topological phase transition and reduces the number of spurious, low energy modes that hamper observation and utilization of Majorana zero modes. Finally, I show that the presence of multiple Majorana modes in a strongly correlated superconducting island leads to Kondo-like behavior with a topological twist.

Topological Phases of Matter

Topological Phases of Matter PDF Author: Roderich Moessner
Publisher: Cambridge University Press
ISBN: 1107105536
Category : Mathematics
Languages : en
Pages : 393

Get Book Here

Book Description
This important graduate level text unites the physical mechanisms behind the phenomena of topological matter within a theoretical framework.

Topological Insulators

Topological Insulators PDF Author: Gregory Tkachov
Publisher: CRC Press
ISBN: 9814613266
Category : Science
Languages : en
Pages : 180

Get Book Here

Book Description
This book is the result of dynamic developments that have occurred in condensed matter physics after the recent discovery of a new class of electronic materials: topological insulators. A topological insulator is a material that behaves as a band insulator in its interior, while acting as a metallic conductor at its surface. The surface current car

Topological Matter

Topological Matter PDF Author: Dario Bercioux
Publisher: Springer
ISBN: 3319763881
Category : Technology & Engineering
Languages : en
Pages : 261

Get Book Here

Book Description
This book covers basic and advanced aspects in the field of Topological Matter. The chapters are based on the lectures presented during the Topological Matter School 2017. It provides graduate level content introducing the basic concepts of the field, including an introductory session on group theory and topological classification of matter. Different topological phases such as Weyls semi-metals, Majoranas fermions and topological superconductivity are also covered. A review chapter on the major experimental achievements in the field is also provided. The book is suitable not only for master, graduate and young postdoctoral researchers, but also to senior scientists who want to acquaint themselves with the subject.

QUANTUM TRANSPORT IN TOPOLOGICAL MATERIALS.

QUANTUM TRANSPORT IN TOPOLOGICAL MATERIALS. PDF Author: Run Xiao
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

Get Book Here

Book Description
This dissertation focuses on the synthesis, characterization, fabrication, and electrical transport measurements of topological materials, including magnetically doped topological insulators and Dirac semimetal Cd3As2. Bismuth-chalcogenide topological insulators have time-reversal-symmetry-protected surface states due to the strong spin-orbit coupling. Breaking the time-reversal symmetry by magnetic dopants can lead to fascinating exotic phenomena, such as the quantum anomalous Hall effect. On the other hand, Dirac semimetals host three-dimensional Dirac fermions and can be identified as a parent phase of other topological phases, such as Weyl semimetals. In this dissertation, quantum transport measurements are performed on thin films of topological materials to investigate and understand the unusual electronic states that host these topological phases. These studies can motivate and facilitate the development of potential applications of topological materials, especially in spintronics and quantum computing. The first topological material studied in this dissertation is a magnetically doped topological insulator system: Cr doped (Bi,Sb)2Te3 - (Bi,Sb)2Te3 - Cr doped (Bi,Sb)2Te3 sandwich heterostructure. By tuning the chemical and asymmetric potentials using dual gates, both the quantum anomalous hall effect, due to the topology in the momentum space, and the topological Hall effect, due to the topology in real space, can be observed in this heterostructure system. We also mapped out a phase diagram of the topological Hall and quantum anomalous Hall effects as a function of the chemical and asymmetry potentials, paving a way to understand and manipulate the chiral magnetic spin textures in real space. The second topological material is Dirac semimetal Cd3As2. We investigated the integer quantum Hall effect in Cd3As2 thin films under strong to moderate quantum confinement (thicknesses of 10 nm, 12 nm, and 15 nm). In all the films, we observed the integer quantum Hall effect in the spin-polarized lowest Landau level (filling factor [nu]=1) and at spin-degenerate higher index Landau levels with even filling factors ([nu]=2,4,6). We also observed the lifting of the Landau level spin degeneracy at v=3 with strong quantum confinement. A tight-binding calculation suggests that the enhanced g-factor due to the quantum confinement and corrections from nearby subbands can be the reason for the emergence of v=3 quantum Hall plateau. Last, we explored the introduction of the transition metal Mn into Cd3As2 thin films to break the time-reversal symmetry. Scanning transmission electron microscopy of these films shows a formation of an Mn-rich layer on top of a pure Cd3As2 layer using both uniform and delta doping methods. The low solubility of Mn in Cd3As2 can be the reason for the phase separation. The Mn-rich region shows out-of-plane magnetic anisotropy in superconducting quantum interference device magnetometry measurements. Moreover, the presence of the Mn surfactant lowers the carrier density in the Cd3As2 layer, and an incipient quantum Hall effect can be observed in low-temperature transport measurements.

Topological Phases of Matter

Topological Phases of Matter PDF Author: Roderich Moessner
Publisher: Cambridge University Press
ISBN: 1009038699
Category : Science
Languages : en
Pages : 393

Get Book Here

Book Description
Topological Phases of Matter are an exceptionally dynamic field of research: several of the most exciting recent experimental discoveries and conceptual advances in modern physics have originated in this field. These have generated new, topological, notions of order, interactions and excitations. This text provides an accessible, unified and comprehensive introduction to the phenomena surrounding topological matter, with detailed expositions of the underlying theoretical tools and conceptual framework, alongside accounts of the central experimental breakthroughs. Among the systems covered are topological insulators, magnets, semimetals, and superconductors. The emergence of new particles with remarkable properties such as fractional charge and statistics is discussed alongside possible applications such as fault-tolerant topological quantum computing. Suitable as a textbook for graduate or advanced undergraduate students, or as a reference for more experienced researchers, the book assumes little prior background, providing self-contained introductions to topics as varied as phase transitions, superconductivity, and localisation.

Quantum Transport in 2 and 3 Dimensional Topological Insulators

Quantum Transport in 2 and 3 Dimensional Topological Insulators PDF Author: Di Xiao
Publisher:
ISBN:
Category :
Languages : en
Pages :

Get Book Here

Book Description
Topological insulators are materials that are insulating in the bulk but that conduct via topologically protected states on the boundary. The concept of topology in condensed matter physics was first introduced to explain the integer quantum Hall (IQH) effect. The perfect quantization of these topologically protected edge states, insensitive to sample geometry and disorder, stimulated an extensive search for many exciting new topological materials. One of the milestones along the journey was the theoretical prediction and experimental discovery of Z2 topological insulators.The first class of Z2 topological insulators discovered was the 2-dimensional topological insulator (2D TI), also known as the quantum spin Hall (QSH) insulator. The 2D TI can be viewed as a variation of the IQH system but with time-reversal-symmetry (TRS). The topological invariant for a 2D TI is the Z2 number, defined by its nontrivial band structure instead of the Chern number in the IQH case. Generalizing this idea to 3 dimensions led to the discovery of the 3D TI with four Z2 invariants. Both the 2D and 3D TIs are of interest as model platforms for testing theoretical problems of fundamental interest. For instance, they allow us to realize artificial condensed matter analogs of fundamental particles such as Majorana fermions and axions that have yet to be observed in nature. They are also of interest for potential technological applications, principally spintronics and quantum computing.This dissertation focuses on the synthesis, characterization, and transport properties of both 2D and 3D TIs. We first discuss the 2D TI candidate material system, type II InAs/GaSb quantum wells, which exhibits a rich topological phase diagram that can be tuned by several parameters such as sample geometry or electrostatic gating. By changing the thicknesses of relevant layers, we are able to enter a new insulating regime where unexpected high-density quantum oscillations are observed. We elucidate this phenomenon through theoretical calculation and through control experiments. The seemingly controversial coexistence of high density states and the insulating regime can be explained by the effect of the attractive Coulomb interaction, which was not considered in earlier theories.The second topic we address is quantum transport in 3D TI systems. Breaking the TRS of the 3D TI surface states leads to many exotic phenomena, including the quantum anomalous Hall (QAH) effect and the axion insulator state. By constructing a sandwich heterostructure that has different magnetic coercive fields in the top and bottom magnetic layers, while keeping the center layer free from magnetic impurities, both the QAH and the axion insulator state can be observed in low-temperature transport measurements, when the magnetization alignment of the top and bottom layers is parallel and antiparallel, respectively. We also discuss the scaling behavior of the topological quantum phase transition between these two states.

Topology in Condensed Matter

Topology in Condensed Matter PDF Author: Michael I. Monastyrsky
Publisher: Springer Science & Business Media
ISBN: 3540312641
Category : Science
Languages : en
Pages : 263

Get Book Here

Book Description
This book reports new results in condensed matter physics for which topological methods and ideas are important. It considers, on the one hand, recently discovered systems such as carbon nanocrystals and, on the other hand, new topological methods used to describe more traditional systems such as the Fermi surfaces of normal metals, liquid crystals and quasicrystals. The authors of the book are renowned specialists in their fields and present the results of ongoing research, some of it obtained only very recently and not yet published in monograph form.

Nonequilibrium Quantum Transport Theory Of Spinful And Topological Systems: A New Perspective And Foundation For Topotronics

Nonequilibrium Quantum Transport Theory Of Spinful And Topological Systems: A New Perspective And Foundation For Topotronics PDF Author: Felix A Buot
Publisher: World Scientific
ISBN: 9811264732
Category : Science
Languages : en
Pages : 594

Get Book Here

Book Description
This book employs nonequilibrium quantum transport, based on the use of mixed Hilbert space representations and real time quantum superfield transport theory, to explain various topological phases of systems with entangled chiral degrees of freedom. It presents an entirely new perspective on topological systems, entanglement-induced localization and delocalization, integer quantum Hall effect (IQHE), fractional quantum Hall effect (FQHE), and its respective spectral zones in the Hofstadter butterfly spectrum. A simple and powerful, intuitive, and wide-ranging perspective on chiral transport dynamics.

Quantum Transport in Topological Matter

Quantum Transport in Topological Matter PDF Author: Jorrit Cornelis de Boer
Publisher:
ISBN: 9789036548120
Category :
Languages : en
Pages : 118

Get Book Here

Book Description