scholarly journals Giant room temperature anomalous Hall effect and tunable topology in a ferromagnetic topological semimetal Co2MnAl

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Peigang Li ◽  
Jahyun Koo ◽  
Wei Ning ◽  
Jinguo Li ◽  
Leixin Miao ◽  
...  
Keyword(s):  
Hall Effect ◽  
Room Temperature ◽  
Transport Phenomena ◽  
Surface States ◽  
Anomalous Hall Effect ◽  
Spintronic Devices ◽  
Structure Topology ◽  
Weyl Semimetal ◽  
Weyl Semimetals ◽  
Record Value

Abstract Weyl semimetals exhibit unusual surface states and anomalous transport phenomena. It is hard to manipulate the band structure topology of specific Weyl materials. Topological transport phenomena usually appear at very low temperatures, which sets challenges for applications. In this work, we demonstrate the band topology modification via a weak magnetic field in a ferromagnetic Weyl semimetal candidate, Co2MnAl, at room temperature. We observe a tunable, giant anomalous Hall effect (AHE) induced by the transition involving Weyl points and nodal rings. The AHE conductivity is as large as that of a 3D quantum AHE, with the Hall angle (ΘH) reaching a record value ($$\tan {\Theta }^{H}=0.21$$ tan Θ H = 0.21 ) at the room temperature among magnetic conductors. Furthermore, we propose a material recipe to generate large AHE by gaping nodal rings without requiring Weyl points. Our work reveals an intrinsically magnetic platform to explore the interplay between magnetic dynamics and topological physics for developing spintronic devices.

scholarly journals Magnetic Weyl semimetal phase in a Kagomé crystal

Science ◽  
2019 ◽  
Vol 365 (6459) ◽  
pp. 1282-1285 ◽  
Author(s):  
D. F. Liu ◽  
A. J. Liang ◽  
E. K. Liu ◽  
Q. N. Xu ◽  
Y. W. Li ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Characteristic Surface ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Weyl Semimetal ◽  
Fermi Arcs ◽  
Weyl Semimetals ◽  
Ferromagnetic Crystal ◽  
Bulk Band

Weyl semimetals are crystalline solids that host emergent relativistic Weyl fermions and have characteristic surface Fermi-arcs in their electronic structure. Weyl semimetals with broken time reversal symmetry are difficult to identify unambiguously. In this work, using angle-resolved photoemission spectroscopy, we visualized the electronic structure of the ferromagnetic crystal Co3Sn2S2 and discovered its characteristic surface Fermi-arcs and linear bulk band dispersions across the Weyl points. These results establish Co3Sn2S2 as a magnetic Weyl semimetal that may serve as a platform for realizing phenomena such as chiral magnetic effects, unusually large anomalous Hall effect and quantum anomalous Hall effect.

scholarly journals Berry curvature origin of the thickness-dependent anomalous Hall effect in a ferromagnetic Weyl semimetal

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Yao Zhang ◽  
Yuefeng Yin ◽  
Guy Dubuis ◽  
Tane Butler ◽  
Nikhil V. Medhekar ◽  
...  
Keyword(s):  
Band Structure ◽  
Hall Effect ◽  
Room Temperature ◽  
Anomalous Hall Effect ◽  
Berry Curvature ◽  
Weyl Semimetal ◽  
Hall Angle ◽  
20 Nm ◽  
Structure Calculations ◽  
Spin Contribution

AbstractMagnetic Weyl semimetals with spontaneously broken time-reversal symmetry exhibit a large intrinsic anomalous Hall effect originating from the Berry curvature. To employ this large Hall current for room temperature topo-spintronics applications, it is necessary to fabricate these materials as thin or ultrathin films. Here, we experimentally demonstrate that Weyl semimetal Co2MnGa thin films (20–50 nm) show a large anomalous Hall angle ~11.4% at low temperature and ~9.7% at room temperature, which can be ascribed to the non-trivial topology of the band structure with large intrinsic Berry curvature. However, the anomalous Hall angle decreases significantly with thicknesses below 20 nm, which band structure calculations confirm is due to the reduction of the majority spin contribution to the Berry curvature. Our results suggest that Co2MnGa is an excellent material to realize room temperature topo-spintronics applications; however, the significant thickness dependence of the Berry curvature has important implications for thin-film device design.

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.

Robust Anomalous Hall Effect and Temperature-Driven Lifshitz Transition in Weyl Semimetal Mn3Ge

Nanoscale ◽  
2021 ◽  
Author(s):  
Xiaolei Wang ◽  
Dong Pan ◽  
Qingqi Zeng ◽  
Xue Chen ◽  
Hailong Wang ◽  
...  
Keyword(s):  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Weyl Semimetal ◽  
Lifshitz Transition ◽  
Weyl Semimetals

Topological Weyl semimetals have attracted lots of interests, because they provide underlying physics and device potential in spintronics. Large anomalous Hall effect (AHE) in non-collinear antiferromagnets (AFMs) represents a striking...

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 Noncollinear ferromagnetic Weyl semimetal with anisotropic anomalous Hall effect

2021 ◽  
Vol 103 (11) ◽  
Author(s):  
Hung-Yu Yang ◽  
Bahadur Singh ◽  
Jonathan Gaudet ◽  
Baozhu Lu ◽  
Cheng-Yi Huang ◽  
...  
Keyword(s):  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Weyl Semimetal

scholarly journals Magnetoresistance and anomalous Hall effect in micro-ribbons of the magnetic Weyl semimetal Co3Sn2S2

2019 ◽  
Vol 114 (9) ◽  
pp. 092403 ◽  
Author(s):  
K. Geishendorf ◽  
R. Schlitz ◽  
P. Vir ◽  
C. Shekhar ◽  
C. Felser ◽  
...  
Keyword(s):  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Weyl Semimetal

Intrinsic photoinduced anomalous Hall effect in insulating GaAs/AlGaAs quantum wells at room temperature

2013 ◽  
Vol 102 (20) ◽  
pp. 202408 ◽  
Author(s):  
J. L. Yu ◽  
Y. H. Chen ◽  
Y. Liu ◽  
C. Y. Jiang ◽  
H. Ma ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Hall Effect ◽  
Room Temperature ◽  
Anomalous Hall Effect

scholarly journals Progress Review on Topological Properties of Heusler Materials

2020 ◽  
Vol 213 ◽  
pp. 02016
Author(s):  
Zhi Lin
Keyword(s):  
Hall Effect ◽  
Surface States ◽  
Anomalous Hall Effect ◽  
Edge State ◽  
Chiral Anomaly ◽  
Dirac Fermion ◽  
High Symmetry ◽  
Heusler Compounds ◽  
Topological Properties ◽  
Topological State

Starting from crystal, electronic and magnetic structures of Heusler compounds, this paper studies the new topological materials related to Heusler compounds and their topological properties, such as anomalous Hall effect, skyrmions, chiral anomaly, Dirac fermion, Weyl fermion, transverse Nernst thermoelectric effect, thermal spintronics and topological surface states. It can be discovered that the topological state of Heusler compound can be well protected due to its high symmetry, thus producing rich topological properties. Heusler materials belonged to Weyl semimetals usually have strong anomalous Hall effect, and the Heusler materials with doping or Anomalous Nernst Effect (ANE) usually have higher thermoelectric figure of merit. These anomalous effects are closely related to the strong spin–orbit interaction. In application, people can use the non-dissipative edge state of quantum anomalous Hall effect to develop a new generation of low-energy transistors and electronic devices. The conversion efficiency of thermoelectric materials can be improved by ANE, and topological superconductivity can be used to promote the progress of quantum computation.

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