scholarly journals Hall Effect and Orbital Magnetism of Binary Alloys

1970 ◽  
Vol 44 (4) ◽  
pp. 879-898 ◽  
Author(s):  
Hidetoshi Fukuyama
Keyword(s):  
Hall Effect ◽  
Binary Alloys ◽  
Orbital Magnetism

scholarly journals Spin-polarized Dirac cone, flat band and saddle point in kagome magnet YMn6Sn6

2020 ◽  
Author(s):  
Man Li ◽  
Qi Wang ◽  
Guangwei Wang ◽  
Zhihong Yuan ◽  
Wenhua Song ◽  
...  
Keyword(s):  
Saddle Point ◽  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Flat Band ◽  
Dirac Fermion ◽  
Kagome Lattice ◽  
Dirac Cone ◽  
Kagomé Lattice ◽  
Orbital Magnetism ◽  
Spin Polarized

Abstract Kagome-lattice of 3d-transition metals hosting Weyl/Dirac fermions and topological flat bands exhibit non-trivial topological characters and novel quantum phases, such as anomalous Hall effect and fractional quantum Hall effect. With consideration of spin-orbit coupling and electron correlation, several instabilities could be induced. The complete characters of the electronic structure of kagome lattice, i.e. the saddle point, Dirac-cone, and flat band, around the Fermi energy (EF) remain elusive in magnetic kagome materials. We present the first experimental observation of the complete features in ferromagnetic kagome layers of YMn6Sn6 helically coupled along the c-axis, by using angle-resolved photoemission spectroscopy and band structure calculations. We demonstrate a Dirac dispersion near EF arising from a spin-polarized orbital, which carries an intrinsic Berry curvature and contributes to the anomalous Hall effect in transport measurements. In addition, a flat band and a saddle point with a high density of states and with orbital-selective characters near EF are observed. These multi-orbital kagome features could cause multi-orbital magnetism. The Dirac fermion, flat band and saddle point in the vicinity of EF open an opportunity in manipulating the topological properties in magnetic materials.

scholarly journals Large spin-Hall effect in non-equilibrium binary copper alloys beyond the solubility limit

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Hiroto Masuda ◽  
Rajkumar Modak ◽  
Takeshi Seki ◽  
Ken-ichi Uchida ◽  
Yong-Chang Lau ◽  
...  
Keyword(s):  
Hall Effect ◽  
High Performance ◽  
Copper Alloys ◽  
Binary Alloys ◽  
Solubility Limit ◽  
Spin Hall Effect ◽  
Thin Film Fabrication ◽  
Combinatorial Technique ◽  
Large Spin ◽  
Non Equilibrium

Abstract Non-magnetic materials exhibiting large spin-Hall effect (SHE) are eagerly desired for high-performance spintronic devices. Here, we report that non-equilibrium Cu-Ir binary alloys with compositions beyond the solubility limit are candidates as spin-Hall materials, even though Cu and Ir do not exhibit remarkable SHE themselves. Thanks to non-equilibrium thin film fabrication, the Cu-Ir binary alloys are obtained over a wide composition range even though they are thermodynamically unstable in bulk form. We investigate the SHE of Cu-Ir by exploiting a combinatorial technique based on spin Peltier imaging, and find that the optimum Ir concentration for enhancing SHE is around 25 at.%. We achieve a large spin-Hall angle of 6.29 ± 0.19% for Cu76Ir24. In contrast to Cu-Ir, non-equilibrium Cu-Bi binary alloys do not show remarkable SHE. Our discovery opens a new direction for the exploration of spin-Hall materials.

Anomalous Hall effect in SmN: Influence of orbital magnetism and 4f -band conduction

2018 ◽  
Vol 98 (23) ◽  
Author(s):  
W. F. Holmes-Hewett ◽  
F. H. Ullstad ◽  
B. J. Ruck ◽  
F. Natali ◽  
H. J. Trodahl
Keyword(s):  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Orbital Magnetism ◽  
Band Conduction

scholarly journals Bulk valley transport and Berry curvature spreading at the edge of flat bands

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Subhajit Sinha ◽  
Pratap Chandra Adak ◽  
R. S. Surya Kanthi ◽  
Bheema Lingam Chittari ◽  
L. D. Varma Sangani ◽  
...  
Keyword(s):  
Hall Effect ◽  
Recent Observation ◽  
High Sensitivity ◽  
Anomalous Hall Effect ◽  
Bilayer Graphene ◽  
Flat Band ◽  
Berry Curvature ◽  
Flat Bands ◽  
Current Path ◽  
Orbital Magnetism

Abstract 2D materials based superlattices have emerged as a promising platform to modulate band structure and its symmetries. In particular, moiré periodicity in twisted graphene systems produces flat Chern bands. The recent observation of anomalous Hall effect (AHE) and orbital magnetism in twisted bilayer graphene has been associated with spontaneous symmetry breaking of such Chern bands. However, the valley Hall state as a precursor of AHE state, when time-reversal symmetry is still protected, has not been observed. Our work probes this precursor state using the valley Hall effect. We show that broken inversion symmetry in twisted double bilayer graphene (TDBG) facilitates the generation of bulk valley current by reporting experimental evidence of nonlocal transport in a nearly flat band system. Despite the spread of Berry curvature hotspots and reduced quasiparticle velocities of the carriers in these flat bands, we observe large nonlocal voltage several micrometers away from the charge current path — this persists when the Fermi energy lies inside a gap with large Berry curvature. The high sensitivity of the nonlocal voltage to gate tunable carrier density and gap modulating perpendicular electric field makes TDBG an attractive platform for valley-twistronics based on flat bands.

scholarly journals Dirac cone, flat band and saddle point in kagome magnet YMn6Sn6

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Man Li ◽  
Qi Wang ◽  
Guangwei Wang ◽  
Zhihong Yuan ◽  
Wenhua Song ◽  
...  
Keyword(s):  
Saddle Point ◽  
Hall Effect ◽  
Theoretical Calculations ◽  
Anomalous Hall Effect ◽  
Flat Band ◽  
Dirac Fermion ◽  
Dirac Fermions ◽  
Dirac Cone ◽  
Fractional Quantum Hall ◽  
Orbital Magnetism

AbstractKagome-lattices of 3d-transition metals hosting Weyl/Dirac fermions and topological flat bands exhibit non-trivial topological characters and novel quantum phases, such as the anomalous Hall effect and fractional quantum Hall effect. With consideration of spin–orbit coupling and electron correlation, several instabilities could be induced. The typical characters of the electronic structure of a kagome lattice, i.e., the saddle point, Dirac-cone, and flat band, around the Fermi energy (EF) remain elusive in magnetic kagome materials. We present the experimental observation of the complete features in ferromagnetic kagome layers of YMn6Sn6 helically coupled along the c-axis, by using angle-resolved photoemission spectroscopy and band structure calculations. We demonstrate a Dirac dispersion near EF, which is predicted by spin-polarized theoretical calculations, carries an intrinsic Berry curvature and contributes to the anomalous Hall effect in transport measurements. In addition, a flat band and a saddle point with a high density of states near EF are observed. These multi-sets of kagome features are of orbital-selective origin and could cause multi-orbital magnetism. The Dirac fermion, flat band and saddle point in the vicinity of EF open an opportunity in manipulating the topological properties in magnetic materials.

scholarly journals Mixed topology ring states for Hall effect and orbital magnetism in skyrmions of Weyl semimetals

2020 ◽  
Vol 102 (18) ◽  
Author(s):  
M. Redies ◽  
F. R. Lux ◽  
J.-P. Hanke ◽  
P. M. Buhl ◽  
S. Blügel ◽  
...  
Keyword(s):  
Hall Effect ◽  
Orbital Magnetism ◽  
Weyl Semimetals
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