scholarly journals Anomalous Hall effect and transport properties of ultra-thin Fe65Co35 films

2020 ◽  
Vol 54 (5) ◽  
pp. 651-653
Author(s):  
H. Li ◽  
Y. Han ◽  
X. Ren ◽  
Z. Tao ◽  
K. Zhang
Keyword(s):  
Hall Effect ◽  
Transport Properties ◽  
Anomalous Hall Effect

scholarly journals Transport Properties of Rare Earth Nitrides

2021 ◽  
Author(s):  
◽  
William Holmes-Hewett
Keyword(s):  
Angular Momentum ◽  
Rare Earth ◽  
Hall Effect ◽  
Transport Properties ◽  
Conduction Band ◽  
Anomalous Hall Effect ◽  
Optical Measurements ◽  
Rare Earth Nitrides ◽  
Heavily Doped ◽  
Majority Spin

<p>In this thesis we investigate the transport properties of SmN, NdN and GdN, members of the rare earth nitride series of intrinsic ferromagnetic semiconductors. GdN is the central member of the series with seven occupied majority spin 4f states and seven empty minority spin 4f states. Both the filled and unfilled 4f states are some few eV away from the conduction and valence band extrema, resulting in transport properties which are dominated by the extended Gd 5d band. The half filled 4f shell, with zero net orbital angular momentum, furthermore simplifies calculations and as such GdN is the most studied both experimentally and in theory. As one moves to lighter members, the filled 4f states become unfilled states in the conduction band and the 4f shell now has a net orbital angular momentum. Calculations concerning these members are now significantly more complicated, and as such there exists a wide range of predictions concerning the conduction band minima in the lighter rare earth nitrides. To inform the current theoretical and experimental literature we report on three studies concerning the transport properties of SmN, NdN and GdN.  To begin we report on the anomalous Hall effect in SmN, NdN and GdN. Under the symmetry of the rock-salt rare earth nitrides the magnitude of the anomalous Hall effect can imply the wave function of the conduction electron (i.e. d or f band). Measurements of the anomalous Hall effect in moderately doped samples are used to show the conduction channel in SmN and NdN is an f band or hybridised f/d band. Furthermore the sign of the anomalous Hall effect can be used to determine the orientation of the spin magnetic moment of the conduction electrons. Optical measurements of SmN, NdN and GdN films are then reported. Optical measurements provide a probe of the band structure of a material via direct transitions between the valence and conduction bands. Measurements of reflectivity and transmission on undoped SmN and NdN films were used to locate the unfilled majority spin 4f bands which form the conduction band minima in each material. Finally a preliminary study of heavily doped SmN, NdN and GdN is discussed. Structural measurements show a reduced lattice parameter while transport results find a significantly enhanced conductivity in heavily doped films. The Curie temperature is found to be enhanced and optical measurements show an increased absorption and red-shifted optical edge in doped films. The superconducting state of SmN is discussed and it is shown only to be present in moderately doped films, i.e. superconductivity is not present in undoped or degenerately doped SmN, within our measurement limits.</p>

scholarly journals Transport Properties in Magnetized Compact Stars

Particles ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 63-74
Author(s):  
Toshitaka Tatsumi ◽  
Hiroaki Abuki
Keyword(s):  
Hall Effect ◽  
Transport Properties ◽  
Condensed Matter ◽  
Anomalous Hall Effect ◽  
Compact Stars ◽  
Kubo Formula ◽  
Chiral Phase ◽  
Dense Quark Matter ◽  
Weyl Semimetals ◽  
The One

Transport properties of dense quark matter are discussed in the strong magnetic field, B. B dependence as well as density dependence of the Hall conductivity is discussed, based on the microscopic Kubo formula. We took into account the possibility of the inhomogeneous chiral phase at moderate densities, where anomalous Hall effect is intrinsic and resembles the one in Weyl semimetals in condensed matter physics. Some theoretical aspects inherent in anomalous Hall effect are also discussed.

Transport Properties of SnTe-MnTe System: Anomalous Hall Effect

1979 ◽  
Vol 47 (6) ◽  
pp. 1879-1886 ◽  
Author(s):  
Masasi Inoue ◽  
Masahiro Tanabe ◽  
Hisao Yagi ◽  
Toshiaki Tatsukawa
Keyword(s):  
Hall Effect ◽  
Transport Properties ◽  
Anomalous Hall Effect

Transport Properties of Rare Earth Nitrides

2021 ◽  
Author(s):  
◽  
William Holmes-Hewett
Keyword(s):  
Angular Momentum ◽  
Rare Earth ◽  
Hall Effect ◽  
Transport Properties ◽  
Conduction Band ◽  
Anomalous Hall Effect ◽  
Optical Measurements ◽  
Rare Earth Nitrides ◽  
Heavily Doped ◽  
Majority Spin

<p>In this thesis we investigate the transport properties of SmN, NdN and GdN, members of the rare earth nitride series of intrinsic ferromagnetic semiconductors. GdN is the central member of the series with seven occupied majority spin 4f states and seven empty minority spin 4f states. Both the filled and unfilled 4f states are some few eV away from the conduction and valence band extrema, resulting in transport properties which are dominated by the extended Gd 5d band. The half filled 4f shell, with zero net orbital angular momentum, furthermore simplifies calculations and as such GdN is the most studied both experimentally and in theory. As one moves to lighter members, the filled 4f states become unfilled states in the conduction band and the 4f shell now has a net orbital angular momentum. Calculations concerning these members are now significantly more complicated, and as such there exists a wide range of predictions concerning the conduction band minima in the lighter rare earth nitrides. To inform the current theoretical and experimental literature we report on three studies concerning the transport properties of SmN, NdN and GdN.  To begin we report on the anomalous Hall effect in SmN, NdN and GdN. Under the symmetry of the rock-salt rare earth nitrides the magnitude of the anomalous Hall effect can imply the wave function of the conduction electron (i.e. d or f band). Measurements of the anomalous Hall effect in moderately doped samples are used to show the conduction channel in SmN and NdN is an f band or hybridised f/d band. Furthermore the sign of the anomalous Hall effect can be used to determine the orientation of the spin magnetic moment of the conduction electrons. Optical measurements of SmN, NdN and GdN films are then reported. Optical measurements provide a probe of the band structure of a material via direct transitions between the valence and conduction bands. Measurements of reflectivity and transmission on undoped SmN and NdN films were used to locate the unfilled majority spin 4f bands which form the conduction band minima in each material. Finally a preliminary study of heavily doped SmN, NdN and GdN is discussed. Structural measurements show a reduced lattice parameter while transport results find a significantly enhanced conductivity in heavily doped films. The Curie temperature is found to be enhanced and optical measurements show an increased absorption and red-shifted optical edge in doped films. The superconducting state of SmN is discussed and it is shown only to be present in moderately doped films, i.e. superconductivity is not present in undoped or degenerately doped SmN, within our measurement limits.</p>

scholarly journals Interface-induced sign reversal of the anomalous Hall effect in magnetic topological insulator heterostructures

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Fei Wang ◽  
Xuepeng Wang ◽  
Yi-Fan Zhao ◽  
Di Xiao ◽  
Ling-Jie Zhou ◽  
...  
Keyword(s):  
Hall Effect ◽  
Electric Fields ◽  
First Principles ◽  
Berry Phase ◽  
Condensed Matter ◽  
Anomalous Hall Effect ◽  
First Principles Calculations ◽  
Sign Reversal ◽  
Berry Curvature ◽  
Topological Materials

AbstractThe Berry phase picture provides important insights into the electronic properties of condensed matter systems. The intrinsic anomalous Hall (AH) effect can be understood as the consequence of non-zero Berry curvature in momentum space. Here, we fabricate TI/magnetic TI heterostructures and find that the sign of the AH effect in the magnetic TI layer can be changed from being positive to negative with increasing the thickness of the top TI layer. Our first-principles calculations show that the built-in electric fields at the TI/magnetic TI interface influence the band structure of the magnetic TI layer, and thus lead to a reconstruction of the Berry curvature in the heterostructure samples. Based on the interface-induced AH effect with a negative sign in TI/V-doped TI bilayer structures, we create an artificial “topological Hall effect”-like feature in the Hall trace of the V-doped TI/TI/Cr-doped TI sandwich heterostructures. Our study provides a new route to create the Berry curvature change in magnetic topological materials that may lead to potential technological applications.

scholarly journals 2D‐Berry‐Curvature‐Driven Large Anomalous Hall Effect in Layered Topological Nodal‐Line MnAlGe

2021 ◽  
pp. 2006301
Author(s):  
Satya N. Guin ◽  
Qiunan Xu ◽  
Nitesh Kumar ◽  
Hsiang‐Hsi Kung ◽  
Sydney Dufresne ◽  
...  
Keyword(s):  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Nodal Line ◽  
Berry Curvature ◽  
Curvature Driven

scholarly journals Anomalous Hall effect in a magnetically extended topological insulator heterostructure

2020 ◽  
Vol 4 (9) ◽  
Author(s):  
Nan Liu ◽  
Xuefan Niu ◽  
Yuxin Liu ◽  
Qinghua Zhang ◽  
Lin Gu ◽  
...  
Keyword(s):  
Hall Effect ◽  
Topological Insulator ◽  
Anomalous Hall Effect
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