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Topological insulators (TIs) are novel materials that manifest spin-polarized Dirac states on their surfaces or at interfaces made with conventional matter. We have measured the electron kinetics of bulk doped TI Bi$_2$Se$_3$ with angle…

Materials Science · Physics 2012-06-07 L. A. Wray , M. Neupane , S. -Y. Xu , Y. -Q. Xia , A. V. Fedorov , H. Lin , S. Basak , A. Bansil , Y. S. Hor , R. J. Cava , M. Z. Hasan

Topological phases arise from the elegant mathematical structures imposed by the interplay between symmetry and topology1-5. From gapped topological insulators to gapless semimetals, topological materials in both quantum and classical…

Topological insulators (TIs) are materials with an insulating bulk characterized by a gapped band structure, along with gapless metallic surface states having a Dirac cone with a helical spin structure in momentum space. The helical…

Materials Science · Physics 2024-09-02 Sumana Paul , Moumita Das , Sujoy Datta , Raja Chakraborty , Prabhat Mandal , P. K. Giri

Discovering Dirac fermions with novel properties has become an important front in condensed matter and materials sciences. Here, we report the observation of unusual Dirac fermion states in a strongly-correlated electron setting, which are…

Graphene and topological insulators (TI) possess two-dimensional Dirac fermions with distinct physical properties. Integrating these two Dirac materials in a single device creates interesting opportunities for exploring new physics of…

Topological insulators represent a new state of matter where the topological nature of the bulk bands dictates the existence of a surface state with unique properties. These materials are predicted to host exotic states such as Majorana…

Materials Science · Physics 2012-05-29 Yoshinori Okada , Wenwen Zhou , Chetan. Dhital , D. Walkup , Ying Ran , Z. Wang , Stephen D. Wilson , V. Madhavan

We discuss the proximate phases of a three-dimensional system with Dirac-like dispersion. Using the cubic lattice with plaquette $\pi$-flux as a model, we find, among others phases, a chiral topological insulator and singlet topological…

Materials Science · Physics 2010-03-11 Pavan Hosur , Shinsei Ryu , Ashvin Vishwanath

A key feature of topological insulators is the robustness of the electron energy spectrum. At a surface of a topological insulator, Dirac point is protected by the characteristic symmetry of the system. The breaking of the symmetry opens a…

Mesoscale and Nanoscale Physics · Physics 2016-12-21 S. Stagraczynski , L. Chotorlishvili , V. K. Dugaev , C. -L. Jia , A. Ernst , A. Komnik , J. Berakdar

Topological insulators are candidates to open up a novel route in spin based electronics. Different to traditional ferromagnetic materials, where the carrier spin-polarization and magnetization are based on the exchange interaction, the…

When electrons are subject to a large external magnetic field, the conventional charge quantum Hall effect \cite{Klitzing,Tsui} dictates that an electronic excitation gap is generated in the sample bulk, but metallic conduction is permitted…

Mesoscale and Nanoscale Physics · Physics 2009-10-08 D. Hsieh , D. Qian , L. Wray , Y. Xia , Y. S. Hor , R. J. Cava , M. Z. Hasan

Dirac cones (DCs) play a pivotal role in various unique phenomena ranging from massless electrons in graphene to robust surface states in topological insulators (TIs). Recent studies have theoretically revealed a full Dirac hierarchy…

Topological insulators (TIs) are emergent materials with unique band structure, which allow the study of quantum effect in solids, as well as contribute to high performance quantum devices. To achieve the better performance of TI, here we…

We characterize the topological insulator Bi$_2$Se$_3$ using time- and angle- resolved photoemission spectroscopy. By employing two-photon photoemission, a complete picture of the unoccupied electronic structure from the Fermi level up to…

The recently discovered three dimensional or bulk topological insulators are expected to exhibit exotic quantum phenomena. It is believed that a trivial insulator can be twisted into a topological state by modulating the spin-orbit…

Mesoscale and Nanoscale Physics · Physics 2011-10-24 Su-Yang Xu , Y. Xia , L. A. Wray , D. Qian , Shuang Jia , J. H. Dil , F. Meier , J. Osterwalder , B. Slomski , H. Lin , R. J. Cava , M. Z. Hasan

In this Rapid Communication we investigate the coupling between excited electrons and phonons in the highly anisotropic electronic structure of the prototypical topological insulator Bi$_2$Te$_3$. Using time- and angle-resolved…

Mesoscale and Nanoscale Physics · Physics 2016-10-13 E. Golias , J. Sánchez-Barriga

Three-dimensional doped Dirac insulators foster simply connected (in both topological and trivial regimes) and annular (deep inside the topological regime) Fermi surfaces (FSs) in the normal state, and allow on-site repulsions among…

Mesoscale and Nanoscale Physics · Physics 2024-11-06 Andras L. Szabo , Bitan Roy

Topological insulators have an insulating bulk but a metallic surface. In the simplest case, the surface electronic structure of a 3D topological insulator is described by a single 2D Dirac cone. A single 2D Dirac fermion cannot be realized…

Mesoscale and Nanoscale Physics · Physics 2013-04-08 Jens H. Bardarson , Joel E. Moore

Understanding Dirac-like Fermions has become an imperative in modern condensed matter sciences: all across its research frontier, from graphene to high T$_c$ superconductors to the topological insulators and beyond, various electronic…

Mesoscale and Nanoscale Physics · Physics 2014-03-25 Oskar Vafek , Ashvin Vishwanath

The surfaces of three-dimensional topological insulators (TIs) characterized by a spin-helical Dirac fermion provide a fertile ground for realizing exotic phenomena as well as having potential for wide-ranging applications. To realize most…

In this article, we propose a practical way to realize topological surface Dirac fermions with tunable attractive interaction between them. The approach involves coating the surface of a topological insulator with a thin film metal and…

Superconductivity · Physics 2025-05-08 Saran Vijayan , Fei Zhou