Giant photoinduced anomalous Hall effect of the topological surface states in three dimensional topological insulators Bi2Te3

2020 ◽  
Vol 116 (14) ◽  
pp. 141603
Author(s):  
Jinling Yu ◽  
Wenyi Wu ◽  
Yumeng Wang ◽  
Kejing Zhu ◽  
Xiaolin Zeng ◽  
...  
Keyword(s):  
Hall Effect ◽  
Topological Insulators ◽  
Three Dimensional ◽  
Surface States ◽  
Anomalous Hall Effect ◽  
Topological Surface

scholarly journals Spectral signatures of the surface anomalous Hall effect in magnetic axion insulators

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mingqiang Gu ◽  
Jiayu Li ◽  
Hongyi Sun ◽  
Yufei Zhao ◽  
Chang Liu ◽  
...  
Keyword(s):  
Hall Effect ◽  
Three Dimensional ◽  
Surface States ◽  
Side Surface ◽  
Anomalous Hall Effect ◽  
Spectral Signatures ◽  
Model Hamiltonian ◽  
Weyl Semimetals ◽  
Significant Step ◽  
Topological Surface

AbstractThe topological surface states of magnetic topological systems, such as Weyl semimetals and axion insulators, are associated with unconventional transport properties such as nonzero or half-quantized surface anomalous Hall effect. Here we study the surface anomalous Hall effect and its spectral signatures in different magnetic topological phases using both model Hamiltonian and first-principles calculations. We demonstrate that by tailoring the magnetization and interlayer electron hopping, a rich three-dimensional topological phase diagram can be established, including three types of topologically distinct insulating phases bridged by Weyl semimetals, and can be directly mapped to realistic materials such as MnBi2Te4/(Bi2Te3)n systems. Among them, we find that the surface anomalous Hall conductivity in the axion-insulator phase is a well-localized quantity either saturated at or oscillating around e2/2h, depending on the magnetic homogeneity. We also discuss the resultant chiral hinge modes embedded inside the side surface bands as the potential experimental signatures for transport measurements. Our study is a significant step forward towards the direct realization of the long-sought axion insulators in realistic material systems.

scholarly journals Natural van der Waals heterostructural single crystals with both magnetic and topological properties

2019 ◽  
Vol 5 (11) ◽  
pp. eaax9989 ◽  
Author(s):  
Jiazhen Wu ◽  
Fucai Liu ◽  
Masato Sasase ◽  
Koichiro Ienaga ◽  
Yukiko Obata ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Hall Effect ◽  
Exchange Coupling ◽  
Van Der Waals ◽  
Surface States ◽  
Anomalous Hall Effect ◽  
Topological Quantum ◽  
Magnetic Layers ◽  
Topological Surface ◽  
Ferromagnetic Hysteresis

Heterostructures having both magnetism and topology are promising materials for the realization of exotic topological quantum states while challenging in synthesis and engineering. Here, we report natural magnetic van der Waals heterostructures of (MnBi2Te4)m(Bi2Te3)n that exhibit controllable magnetic properties while maintaining their topological surface states. The interlayer antiferromagnetic exchange coupling is gradually weakened as the separation of magnetic layers increases, and an anomalous Hall effect that is well coupled with magnetization and shows ferromagnetic hysteresis was observed below 5 K. The obtained homogeneous heterostructure with atomically sharp interface and intrinsic magnetic properties will be an ideal platform for studying the quantum anomalous Hall effect, axion insulator states, and the topological magnetoelectric effect.

scholarly journals Magnetizing topological surface states of Bi2Se3 with a CrI3 monolayer

2019 ◽  
Vol 5 (5) ◽  
pp. eaaw1874 ◽  
Author(s):  
Yusheng Hou ◽  
Jeongwoo Kim ◽  
Ruqian Wu
Keyword(s):  
Density Functional ◽  
Topological Insulators ◽  
Dirac Point ◽  
Surface States ◽  
Anomalous Hall Effect ◽  
Spin Splitting ◽  
Topological Feature ◽  
Topological Parameters ◽  
General Rules ◽  
Topological Surface

To magnetize surfaces of topological insulators without damaging their topological feature is a crucial step for the realization of the quantum anomalous Hall effect (QAHE) and remains as a challenging task. Through density functional calculations, we found that adsorption of a semiconducting two-dimensional van der Waals (2D-vdW) ferromagnetic CrI3 monolayer can create a sizable spin splitting at the Dirac point of the topological surface states of Bi2Se3 films. Furthermore, general rules that connect different quantum and topological parameters are established through model analyses. This work provides a useful guideline for the realization of QAHE at high temperatures in heterostructures of 2D-vdW magnetic monolayers and topological insulators.

scholarly journals Non-Hermiticity and topological invariants of magnon Bogoliubov–de Gennes systems

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Hiroki Kondo ◽  
Yutaka Akagi ◽  
Hosho Katsura
Keyword(s):  
Hall Effect ◽  
Topological Insulators ◽  
Three Dimensional ◽  
Surface States ◽  
Theoretical Models ◽  
Topological Invariant ◽  
Topological Invariants ◽  
Topological Phases ◽  
Ideal Candidate ◽  
Edge Surface

Abstract Since the theoretical prediction and experimental observation of the magnon thermal Hall effect, a variety of novel phenomena that may occur in magnonic systems have been proposed. We review recent advances in the study of topological phases of magnon Bogoliubov–de Gennes (BdG) systems. After giving an overview of previous works on electronic topological insulators and the magnon thermal Hall effect, we provide the necessary background for bosonic BdG systems, with particular emphasis on their non-Hermiticity arising from the diagonalization of the BdG Hamiltonian. We then introduce definitions of $$ \mathbb{Z}_2 $$ topological invariants for bosonic systems with pseudo-time-reversal symmetry, which ensures the existence of bosonic counterparts of “Kramers pairs.” Because of the intrinsic non-Hermiticity of bosonic BdG systems, these topological invariants have to be defined in terms of the bosonic Berry connection and curvature. We then introduce theoretical models that can be thought of as magnonic analogs of two- and three-dimensional topological insulators in class AII. We demonstrate analytically and numerically that the $$ \mathbb{Z}_2 $$ topological invariants precisely characterize the presence of gapless edge/surface states. We also predict that bilayer CrI$$_3$$ with a particular stacking would be an ideal candidate for the realization of a two-dimensional magnon system characterized by a nontrivial $$ \mathbb{Z}_2 $$ topological invariant. For three-dimensional topological magnon systems, the magnon thermal Hall effect is expected to occur when a magnetic field is applied to the surface.

scholarly journals Anomalous Hall effect in Weyl semimetal half-Heusler compounds RPtBi (R = Gd and Nd)

2018 ◽  
Vol 115 (37) ◽  
pp. 9140-9144 ◽  
Author(s):  
Chandra Shekhar ◽  
Nitesh Kumar ◽  
V. Grinenko ◽  
Sanjay Singh ◽  
R. Sarkar ◽  
...  
Keyword(s):  
Hall Effect ◽  
Muon Spin ◽  
Surface States ◽  
Anomalous Hall Effect ◽  
Chiral Anomaly ◽  
Heusler Compounds ◽  
Weyl Semimetal ◽  
Spin Resonance ◽  
Topological Surface ◽  
Topological Semimetals

Topological materials ranging from topological insulators to Weyl and Dirac semimetals form one of the most exciting current fields in condensed-matter research. Many half-Heusler compounds, RPtBi (R = rare earth), have been theoretically predicted to be topological semimetals. Among various topological attributes envisaged in RPtBi, topological surface states, chiral anomaly, and planar Hall effect have been observed experimentally. Here, we report an unusual intrinsic anomalous Hall effect (AHE) in the antiferromagnetic Heusler Weyl semimetal compounds GdPtBi and NdPtBi that is observed over a wide temperature range. In particular, GdPtBi exhibits an anomalous Hall conductivity of up to 60 Ω−1⋅cm−1 and an anomalous Hall angle as large as 23%. Muon spin-resonance (μSR) studies of GdPtBi indicate a sharp antiferromagnetic transition (TN) at 9 K without any noticeable magnetic correlations above TN. Our studies indicate that Weyl points in these half-Heuslers are induced by a magnetic field via exchange splitting of the electronic bands at or near the Fermi energy, which is the source of the chiral anomaly and the AHE.

scholarly journals Discovery of a weak topological insulating state and van Hove singularity in triclinic RhBi2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kyungchan Lee ◽  
Gunnar F. Lange ◽  
Lin-Lin Wang ◽  
Brinda Kuthanazhi ◽  
Thaís V. Trevisan ◽  
...  
Keyword(s):  
Time Reversal ◽  
Topological Insulators ◽  
Dirac Point ◽  
Saddle Points ◽  
Surface States ◽  
Van Hove Singularity ◽  
Space Group ◽  
Topological Materials ◽  
Topological Surface ◽  
Optimal Space

AbstractTime reversal symmetric (TRS) invariant topological insulators (TIs) fullfil a paradigmatic role in the field of topological materials, standing at the origin of its development. Apart from TRS protected strong TIs, it was realized early on that more confounding weak topological insulators (WTI) exist. WTIs depend on translational symmetry and exhibit topological surface states only in certain directions making it significantly more difficult to match the experimental success of strong TIs. We here report on the discovery of a WTI state in RhBi2 that belongs to the optimal space group P$$\bar{1}$$ 1 ¯ , which is the only space group where symmetry indicated eigenvalues enumerate all possible invariants due to absence of additional constraining crystalline symmetries. Our ARPES, DFT calculations, and effective model reveal topological surface states with saddle points that are located in the vicinity of a Dirac point resulting in a van Hove singularity (VHS) along the (100) direction close to the Fermi energy (EF). Due to the combination of exotic features, this material offers great potential as a material platform for novel quantum effects.

Sign in / Sign up

Export Citation Format

Share Document