scholarly journals Two dimensional V2O3 and its experimental feasibility as robust room-temperature magnetic Chern insulator

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Simon Mellaerts ◽  
Ruishen Meng ◽  
Mariela Menghini ◽  
Valeri Afanasiev ◽  
Jin Won Seo ◽  
...  
Keyword(s):  
Room Temperature ◽  
Energy Gap ◽  
Atomic Layer ◽  
Anomalous Hall Effect ◽  
Spin Orbit Coupling ◽  
Edge States ◽  
Spin Polarized ◽  
Small Deformations ◽  
Structurally Stable ◽  
Stable Material

AbstractThe possibility of dissipationless chiral edge states without the need of an external magnetic field in the quantum anomalous Hall effect (QAHE) offers a great potential in electronic/spintronic applications. The biggest hurdle for the realization of a room-temperature magnetic Chern insulator is to find a structurally stable material with a sufficiently large energy gap and Curie temperature that can be easily implemented in electronic devices. This work based on first-principle methods shows that a single atomic layer of V2O3 with honeycomb–kagome (HK) lattice is structurally stable with a spin-polarized Dirac cone which gives rise to a room-temperature QAHE by the existence of an atomic on-site spin–orbit coupling (SOC). Moreover, by a strain and substrate study, it was found that the quantum anomalous Hall system is robust against small deformations and can be supported by a graphene substrate.

Anomalous Magneto-Electric Properties in Chalcopyrite MnGeP2 Films

2017 ◽  
Vol 864 ◽  
pp. 111-115
Author(s):  
Yun Ki Kim ◽  
J.B. Ketterson
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Anomalous Hall Effect ◽  
Alloy Film ◽  
Ferromagnetic Transition ◽  
Field Sweep ◽  
Maximum Change ◽  
Hall Effects ◽  
Spin Polarized ◽  
Field Dependent

We have successfully grown MnGeP2 thin films and Ge and MnGeP2 alloy films on GaAs(100) substrate. Magnetization measurements have been performed on MnGeP2 film samples at temperatures from 5 to 400 K. The measurements have shown that there are a ferromagnetic to paramagnetic transition above room temperature. Field dependent magnetization experiments have shown a coercive field of 160, 1400, 3900 Oe at 300, 250 and 5 K, respectively. A negative magnetoresistance (MR) has been found with a maximum change less than 2% at 5 T and 5 K. The MR measurements on the films have displayed hysteric behaviors with respect to the external field sweep at low fields at temperature below the ferromagnetic transition. Anomalous Hall effects have been found in the MnGeP2 film and Ge and MnGeP2 alloy film samples. Above the transition temperature neither hysteric behavior nor anomalous Hall effect was found. These results imply that spin polarized hole carriers exist in the MnGeP2 films.

scholarly journals High-temperature magnetism and microstructure of a semiconducting ferromagnetic (GaSb)1− x (MnSb) x alloy

2018 ◽  
Vol 9 ◽  
pp. 2457-2465 ◽  
Author(s):  
Leonid N Oveshnikov ◽  
Elena I Nekhaeva ◽  
Alexey V Kochura ◽  
Alexander B Davydov ◽  
Mikhail A Shakhov ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnetic Force ◽  
Composite Films ◽  
High Mobility ◽  
Anomalous Hall Effect ◽  
Columnar Structure ◽  
Magnetic Composite ◽  
Force Microscopy ◽  
Spin Polarized ◽  
Good Agreement

We have studied the properties of relatively thick (about 120 nm) magnetic composite films grown by pulsed laser deposition using the eutectic compound (GaSb)0.59(MnSb)0.41 as target for sputtering. For the studied films we have observed ferromagnetism and an anomalous Hall effect above room temperature, confirming the presence of spin-polarized carriers. Electron microscopy, atomic and magnetic force microscopy results suggest that the films under study have a homogenous columnar structure in the bulk while MnSb inclusions accumulate near the surface. This is in good agreement with the high mobility values of charge carriers. Based on our data we conclude that the magnetic and magnetotransport properties of the films at room temperature are defined by the MnSb inclusions.

Magnetotransport Properties of MnGeAs2 Films

2017 ◽  
Vol 864 ◽  
pp. 116-120
Author(s):  
Yun Ki Kim ◽  
J.B. Ketterson
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Anomalous Hall Effect ◽  
Current Voltage ◽  
Spin Polarized ◽  
Current Voltage Characteristics ◽  
Small Change ◽  
P Type ◽  
Effective Carrier

MnGeAs2 thin films were successfully deposited on GaAs(100) substrate. The films exhibited room-temperature ferromagnetism with TC ~ 330 K, based on both magnetization and resistance measurements at temperatures from 5 to 370 K. The coercive fields at 5 and 300 K were 2100 and 50 Oe. The anomalous Hall effect was observed, suggesting the existence of spin polarized carriers in MnGeAs2 thin films. The magnetoresistance (MR) measurements showed very small change (~ 0.1% at 5 K) in resistance at low temperature. The MR value at 5 K was smaller than that (~ 9% at 305 K) at room temperature (305 K). Type of majority carriers in the films was determined to be n-type by Hall measurement above the transition temperature. The effective carrier density was 1.8´1020 cm-3. The diode current-voltage characteristics were shown in a hetero-junction MnGeAs2 film on a conducting p-type GaAs substrate.

scholarly journals Topological Phase and Quantum Anomalous Hall Effect in Ferromagnetic Transition-Metal Dichalcogenides Monolayer 1T-VSe2

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1998
Author(s):  
Angus Huang ◽  
Chin-Hsuan Chen ◽  
Ching-Hao Chang ◽  
Horng-Tay Jeng
Keyword(s):  
Transition Metal ◽  
Hall Effect ◽  
Transition Metal Dichalcogenides ◽  
Anomalous Hall Effect ◽  
Ferromagnetic Transition ◽  
Spin Orbit Coupling ◽  
Edge States ◽  
Quantum Anomalous Hall Effect ◽  
Metal Dichalcogenides ◽  
Crossing Point

Magnetic two-dimensional (2D) van der Waals materials have attracted tremendous attention because of their high potential in spintronics. In particular, the quantum anomalous Hall (QAH) effect in magnetic 2D layers shows a very promising prospect for hosting Majorana zero modes at the topologically protected edge states in proximity to superconductors. However, the QAH effect has not yet been experimentally realized in monolayer systems to date. In this work, we study the electronic structures and topological properties of the 2D ferromagnetic transition-metal dichalcogenides (TMD) monolayer 1T−VSe2 by first-principles calculations with the Heyd–Scuseria–Ernzerhof (HSE) functional. We find that the spin-orbit coupling (SOC) opens a continuous band gap at the magnetic Weyl-like crossing point hosting the quantum anomalous Hall effect with Chern number C=2. Moreover, we demonstrate the topologically protected edge states and intrinsic (spin) Hall conductivity in this magnetic 2D TMD system. Our results indicate that 1T−VSe2 monolayer serves as a stoichiometric quantum anomalous Hall material.

scholarly journals Fully spin-polarized quadratic non-Dirac bands realized quantum anomalous Hall effect

2020 ◽  
Vol 22 (2) ◽  
pp. 549-555 ◽  
Author(s):  
Ping Li ◽  
Tian-Yi Cai
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Quantum State ◽  
Anomalous Hall Effect ◽  
Edge States ◽  
Quantum Anomalous Hall Effect ◽  
Spin Polarized

The quantum anomalous Hall effect is an intriguing quantum state that exhibits chiral edge states in the absence of a magnetic field.

scholarly journals Magnetic Moments and Electron Transport through Chromium-based Antiferromagnetic Nanojunctions

2018 ◽  
Author(s):  
Marco Bragato ◽  
Simona Achilli ◽  
Fausto Cargnoni ◽  
Davide Ceresoli ◽  
Rocco Martinazzo ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnetic Moments ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Applied Bias ◽  
Spintronic Device ◽  
Ballistic Conductance ◽  
Spin Magnetization ◽  
Spin Polarized ◽  
Large Spin

We report the electronic, magnetic and transport properties of a prototypical antiferromagnetic (AFM) spintronic device. We chose Cr as the active layer because it is the only room-temperature AFM elemental metal. We sandwiched Cr between two non-magnetic metals (Pt or Au) with large spin-orbit coupling. We also inserted a buffer layer of insulating MgO to mimic the structure and finite resistivity of a real device. We found that, while spin-orbit has a negligible effect on the current flowing through the device, the MgO layer plays a crucial role. Its effect is to decouple the Cr magnetic moment from Pt (or Au) and to develop an overall spin magnetization. We have also calculated the spin-polarized ballistic conductance of the device within the Büttiker-Landauer framework, and we have found that for small applied bias our Pt/Cr/MgO/Pt device presents a spin polarization of the current amounting to ~25%.

scholarly journals Magnetic Moments and Electron Transport through Chromium-Based Antiferromagnetic Nanojunctions

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2030 ◽  
Author(s):  
Marco Bragato ◽  
Simona Achilli ◽  
Fausto Cargnoni ◽  
Davide Ceresoli ◽  
Rocco Martinazzo ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnetic Moments ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Applied Bias ◽  
Spintronic Device ◽  
Ballistic Conductance ◽  
Spin Magnetization ◽  
Spin Polarized ◽  
Large Spin

We report the electronic, magnetic and transport properties of a prototypical antiferromagnetic (AFM) spintronic device. We chose Cr as the active layer because it is the only room-temperature AFM elemental metal. We sandwiched Cr between two non-magnetic metals (Pt or Au) with large spin-orbit coupling. We also inserted a buffer layer of insulating MgO to mimic the structure and finite resistivity of a real device. We found that, while spin-orbit has a negligible effect on the current flowing through the device, the MgO layer plays a crucial role. Its effect is to decouple the Cr magnetic moment from Pt (or Au) and to develop an overall spin magnetization. We have also calculated the spin-polarized ballistic conductance of the device within the Büttiker–Landauer framework, and we have found that for small applied bias our Pt/Cr/MgO/Pt device presents a spin polarization of the current amounting to ≃25%.

Clustering-Triggered Efficient Room Temperature Phosphorescence from Nonconventional Luminophores

2019 ◽  
Author(s):  
Shuyuan Zheng ◽  
Taiping Hu ◽  
Xin Bin ◽  
Yunzhong Wang ◽  
Yuanping Yi ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Efficiency ◽  
Spin Orbit Coupling ◽  
Design Rationale ◽  
Emission Mechanism ◽  
Room Temperature Phosphorescence ◽  
Electronic Interactions ◽  
Energy Gaps ◽  
Theoretical Results

Pure organic room temperature phosphorescence (RTP) and luminescence from nonconventional luminophores have gained increasing attention. However, it remains challenging to achieve efficient RTP from unorthodox luminophores, on account of the unsophisticated understanding of the emission mechanism. Here we propose a strategy to realize efficient RTP in nonconventional luminophores through incorporation of lone pairs together with clustering and effective electronic interactions. The former promotes spin-orbit coupling and boost the consequent intersystem crossing, whereas the latter narrows energy gaps and stabilizes the triplets, thus synergistically affording remarkable RTP. Experimental and theoretical results of urea and its derivatives verify the design rationale. Remarkably, RTP from thiourea solids with unprecedentedly high efficiency of up to 24.5% is obtained. Further control experiments testify the crucial role of through-space delocalization on the emission. These results would spur the future fabrication of nonconventional phosphors, and moreover should advance understanding of the underlying emission mechanism.<br>

Multiple Weyl fermions and tunable quantum anomalous Hall effect in 2D half-metal with huge spin-related energy gap

2021 ◽  
Vol 551 ◽  
pp. 149390
Author(s):  
Weizhen Meng ◽  
Xiaoming Zhang ◽  
Weiwang Yu ◽  
Ying Liu ◽  
Lu Tian ◽  
...  
Keyword(s):  
Hall Effect ◽  
Energy Gap ◽  
Anomalous Hall Effect ◽  
Half Metal ◽  
Related Energy ◽  
Quantum Anomalous Hall Effect ◽  
Weyl Fermions
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