The Experts below are selected from a list of 38379 Experts worldwide ranked by ideXlab platform
F S Bergeret - One of the best experts on this subject based on the ideXlab platform.
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very large thermal rectification in ferromagnetic insulator based superconducting tunnel junctions
Applied Physics Letters, 2020Co-Authors: F Giazotto, F S BergeretAbstract:We investigate electronic thermal rectification in ferromagnetic insulator-based superconducting tunnel junctions. Ferromagnetic insulators coupled to superconductors are known to induce sizable Spin Splitting in the superconducting density of states and also lead to efficient Spin filtering if used as tunnel barriers. The combination of Spin Splitting and Spin filtering is shown to yield a substantial amount of self-amplification of the electronic heat diode effect due to breaking of the electron-hole symmetry in the system, which is added to the thermal asymmetry of the junction. Large Spin Splitting and large Spin polarization ( ≳ 90 %) can potentially lead to thermal rectification efficiencies exceeding ∼ 5 × 10 4 % for realistic parameters in a suitable temperature range, thereby outperforming up to a factor of ∼ 250, the heat diode effect achievable with conventional superconducting tunnel junctions. These results are relevant for improved control of heat currents in innovative phase-coherent caloritronic nanodevices and for enhanced thermal management of quantum circuits at the nanoscale.
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very large thermal rectification in ferromagnetic insulator based superconducting tunnel junctions
arXiv: Mesoscale and Nanoscale Physics, 2020Co-Authors: F Giazotto, F S BergeretAbstract:We investigate electronic thermal rectification in ferromagnetic insulator-based superconducting tunnel junctions. Ferromagnetic insulators coupled to superconductors are known to induce sizable Spin Splitting in the superconducting density of states, and also lead to efficient Spin filtering if operated as tunnel barriers. The combination of Spin Splitting and Spin filtering is shown to yield a substantial self-amplification of the electronic heat diode effect due to breaking of the electron-hole symmetry in the system which is added to the thermal asymmetry of the junction. Large Spin Splitting and large Spin polarization can potentially lead to thermal rectification efficiency exceeding 5 .10^4 for realistic parameters in a suitable temperature range, thereby outperforming up to a factor of 250 the heat diode effect achievable with conventional superconducting tunnel junctions. These results could be relevant for improved mastering of the heat currents in innovative phase-coherent caloritronic nanodevices, and for enhanced thermal management of quantum circuits at the nanoscale.
Junhao Chu - One of the best experts on this subject based on the ideXlab platform.
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manipulation of the large rashba Spin Splitting in polar two dimensional transition metal dichalcogenides
Physical Review B, 2017Co-Authors: Qunfang Yao, Jia Cai, Wenyi Tong, Shijing Gong, Jiqing Wang, Xiangang Wan, Chungang Duan, Junhao ChuAbstract:Transition metal dichalcogenide (TMD) monolayers MXY (M=Mo, W, X(not equal to)Y=S, Se, Te) are two-dimensional polar semiconductors. Setting WSeTe monolayer as an example and using density functional theory calculations, we investigate the manipulation of Rashba Spin orbit coupling (SOC) in the MXY monolayer. It is found that the intrinsic out-of-plane electric field due to the mirror symmetry breaking induces the large Rashba Spin Splitting around the Gamma point, which, however, can be easily tuned by applying the in-plane biaxial strain. Through a relatively small strain (from -2% to 2%), a large tunability (from around -50% to 50%) of Rashba SOC can be obtained due to the modified orbital overlap, which can in turn modulate the intrinsic electric field. The orbital selective external potential method further confirms the significance of the orbital overlap between W-dz2 and Se-pz in Rashba SOC. In addition, we also explore the influence of the external electric field on Rashba SOC in the WSeTe monolayer, which is less effective than strain. The large Rashba Spin Splitting, together with the valley Spin Splitting in MXY monolayers may make a special contribution to semiconductor Spintronics and valleytronics.
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manipulation of the large rashba Spin Splitting in polar two dimensional transition metal dichalcogenides
Physical Review B, 2017Co-Authors: Qunfang Yao, Jia Cai, Wenyi Tong, Shijing Gong, Jiqing Wang, Xiangang Wan, Chungang Duan, Junhao ChuAbstract:Transition-metal dichalcogenide (TMD) monolayers $MXY\phantom{\rule{0.16em}{0ex}}(M=\mathrm{Mo},\phantom{\rule{0.16em}{0ex}}\mathrm{W};X\phantom{\rule{0.16em}{0ex}}\ensuremath{\ne}\phantom{\rule{0.16em}{0ex}}Y=\mathrm{S},\phantom{\rule{0.16em}{0ex}}\mathrm{Se},\phantom{\rule{0.16em}{0ex}}\mathrm{Te})$ are two-dimensional polar semiconductors. Setting the WSeTe monolayer as an example and using density functional theory calculations, we investigate the manipulation of Rashba Spin-orbit coupling (SOC) in the MXY monolayer. It is found that the intrinsic out-of-plane electric field due to the mirror symmetry breaking induces the large Rashba Spin Splitting around the $\mathrm{\ensuremath{\Gamma}}$ point, which, however, can be easily tuned by applying the in-plane biaxial strain. Through a relatively small strain (from $\ensuremath{-}2%$ to 2%), a large tunability (from around $\ensuremath{-}50%$ to 50%) of Rashba SOC can be obtained due to the modified orbital overlap, which can in turn modulate the intrinsic electric field. The orbital selective external potential method further confirms the significance of the orbital overlap between $\mathrm{W}\text{\ensuremath{-}}{d}_{{z}^{2}}$ and $\mathrm{Se}\text{\ensuremath{-}}{p}_{z}$ in Rashba SOC. In addition, we also explore the influence of the external electric field on Rashba SOC in the WSeTe monolayer, which is less effective than strain. By calculating the electric-field-induced Rashba SOC in all six $M{X}_{2}$ monolayers, the rule of the electric-field influence on Rashba SOC in TMD monolayers is demonstrated. The large Rashba Spin Splitting, together with the valley Spin Splitting in MXY monolayers, may make a special contribution to semiconductor Spintronics and valleytronics.
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controlling rashba Spin orbit coupling in polar two dimensional transition metal dichalcogenide
arXiv: Computational Physics, 2016Co-Authors: Qunfang Yao, Jia Cai, Wenyi Tong, Shijing Gong, Jiqing Wang, Xiangang Wan, Chungang Duan, Junhao ChuAbstract:Monolayer transition metal dichalcogenide (TMD) group of materials MXY (M=Mo, W, X(not equal to)Y=S, Se, Te) are two-dimensional polar semiconductors with Rashba Spin orbit coupling (SOC). Setting WSeTe as an example and using density functional theory calculations, we investigate the influence of biaxial strain and electric field on Rashba SOC in MXY monolayer. The orbital analysis reveals that Rashba Spin Splitting around Gamma point occurs mainly through the SOC matrix elements between the W-dz2 and -dxz/yz orbitals, and those between the Se-pz and -px/y orbitals. We find the change of local electric field between Se and W atoms arising from the mirror symmetry breaking plays the critical role in forming the large Rashba SOC, and through a relatively small compressive/tensile strain (from -2% to 2%), a large tunability of Rashba SOC can be obtained due to the modified W-Se bonding interaction. In addition, we also explore the influence of electric field on Rashba SOC in WSeTe, which can impact the charge density distribution of the Se and Te atoms, and slightly influence Rashba SOC. The coexistence of large Rashba Spin Splitting and valley Spin Splitting in MXY brings rich Spin-related phenomena, which may make a special contribution to semiconductor Spintronics and valleytronics.
J H Chu - One of the best experts on this subject based on the ideXlab platform.
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anomalous Spin orbit coupling in high density two dimensional electron gas confined in ingaas inalas quantum well
Solid State Communications, 2012Co-Authors: Tie Lin, J H Chu, K H Gao, L M Wei, Xia Liu, X S Chen, Yg 重点实验室 Zhang, Nengli DaiAbstract:Abstract We study the magnetotransport property of a high-density two-dimensional electron gas confined in InGaAs/InAlAs quantum well. Both beating pattern in the Shubnikov–de Hass oscillation of resistivity and weak antilocalization effect are observed. From these two effects, Rashba Spin-Splitting energy is extracted. The extracted Rashba Spin-Splitting energy shows a nonmonotonic dependence on Fermi wave vector, contrary to the prevailing linear Rashba model. This anomalous behavior can be attributed to the nonlinear Rashba Spin-Splitting mechanism [Yang et al., Phys. Rev. B 74 (2006) 193314].
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beating patterns in the oscillatory magnetoresistance originatedfrom zero field Spin Splitting in alxga1 xn gan heterostructures
Applied Physics Letters, 2006Co-Authors: Ning Tang, B G Shen, Maojun Wang, Kui Han, Zhijian Yang, G Y Zhang, Tie Lin, Bin Zhu, Wu Zhou, J H ChuAbstract:Beating patterns in the oscillatory magnetoresistance in Al0.11Ga0.89N∕GaN heterostructures with one subband occupation have been investigated by means of temperature dependent Shubnikov–de Haas measurements at low temperatures and high magnetic fields. The zero-field Spin Splitting effect is observed by excluding the magnetointersubband scattering effect. The obtained zero-field Spin Splitting energy is 2.5meV, and the obtained Spin-orbit coupling parameter is 2.2×10−12eVm. Despite the strong polarization-induced electric field in the heterostructures, the Spin-orbit coupling parameter in AlxGa1−xN∕GaN heterostructures is smaller than that in other heterostructures, such as InxGa1−xAs∕InyAl1−yAs ones. This is due to the large effective mass of the two-dimensional electron gas and the large GaN energy band gap in AlxGa1−xN∕GaN heterostructures. With an increase in magnetic field, the Spin Splitting energy becomes smaller. The zero-field effect is still the dominant mechanism in AlxGa1−xN∕GaN heterostructures at a magnetic field as high as 4.4T.Beating patterns in the oscillatory magnetoresistance in Al0.11Ga0.89N∕GaN heterostructures with one subband occupation have been investigated by means of temperature dependent Shubnikov–de Haas measurements at low temperatures and high magnetic fields. The zero-field Spin Splitting effect is observed by excluding the magnetointersubband scattering effect. The obtained zero-field Spin Splitting energy is 2.5meV, and the obtained Spin-orbit coupling parameter is 2.2×10−12eVm. Despite the strong polarization-induced electric field in the heterostructures, the Spin-orbit coupling parameter in AlxGa1−xN∕GaN heterostructures is smaller than that in other heterostructures, such as InxGa1−xAs∕InyAl1−yAs ones. This is due to the large effective mass of the two-dimensional electron gas and the large GaN energy band gap in AlxGa1−xN∕GaN heterostructures. With an increase in magnetic field, the Spin Splitting energy becomes smaller. The zero-field effect is still the dominant mechanism in AlxGa1−xN∕GaN heterostructu...
Veronika Sunko - One of the best experts on this subject based on the ideXlab platform.
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maximal rashba like Spin Splitting via kinetic energy coupled inversion symmetry breaking
Nature, 2017Co-Authors: Veronika Sunko, H Rosner, Pallavi Kushwaha, Seunghyun Khim, Federico Mazzola, L Bawden, O J Clark, J M Riley, Deepa KasinathanAbstract:Asymmetry in surface hopping energies in different atomic layers of delafossite oxides results in some of the largest known Rashba-like Spin Splittings. The Rashba effect is fundamental to many phenomena in two-dimensional condensed-matter materials and underlies many Spintronics applications. Spin–orbit coupling combined with inversion-symmetry breaking is responsible for the Rashba effect and leads to momentum-dependent Spin Splitting in the solid. Conventionally, materials with particularly large Rashba Spin Splitting are designed by using elements with strong Spin–orbit effects. Here, the authors explore a different strategy that exploits the asymmetry of surface hopping energies. They show that this leads to delafossite oxides with record-breaking Rashba-like Spin Splittings. This work shows new routes towards better Spintronics materials. Engineering and enhancing the breaking of inversion symmetry in solids—that is, allowing electrons to differentiate between ‘up’ and ‘down’—is a key goal in condensed-matter physics and materials science because it can be used to stabilize states that are of fundamental interest and also have potential practical applications. Examples include improved ferroelectrics for memory devices and materials that host Majorana zero modes for quantum computing1,2. Although inversion symmetry is naturally broken in several crystalline environments, such as at surfaces and interfaces, maximizing the influence of this effect on the electronic states of interest remains a challenge. Here we present a mechanism for realizing a much larger coupling of inversion-symmetry breaking to itinerant surface electrons than is typically achieved. The key element is a pronounced asymmetry of surface hopping energies—that is, a kinetic-energy-coupled inversion-symmetry breaking, the energy scale of which is a substantial fraction of the bandwidth. Using Spin- and angle-resolved photoemission spectroscopy, we demonstrate that such a strong inversion-symmetry breaking, when combined with Spin–orbit interactions, can mediate Rashba-like3,4 Spin Splittings that are much larger than would typically be expected. The energy scale of the inversion-symmetry breaking that we achieve is so large that the Spin Splitting in the CoO2- and RhO2-derived surface states of delafossite oxides becomes controlled by the full atomic Spin–orbit coupling of the 3d and 4d transition metals, resulting in some of the largest known Rashba-like3,4 Spin Splittings. The core structural building blocks that facilitate the bandwidth-scaled inversion-symmetry breaking are common to numerous materials. Our findings therefore provide opportunities for creating Spin-textured states and suggest routes to interfacial control of inversion-symmetry breaking in designer heterostructures of oxides and other material classes.
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maximal rashba like Spin Splitting via kinetic energy coupled inversion symmetry breaking
Nature, 2017Co-Authors: Veronika Sunko, H Rosner, Pallavi Kushwaha, Seunghyun Khim, Federico Mazzola, L Bawden, O J Clark, J M Riley, Deepa KasinathanAbstract:Engineering and enhancing the breaking of inversion symmetry in solids-that is, allowing electrons to differentiate between 'up' and 'down'-is a key goal in condensed-matter physics and materials science because it can be used to stabilize states that are of fundamental interest and also have potential practical applications. Examples include improved ferroelectrics for memory devices and materials that host Majorana zero modes for quantum computing. Although inversion symmetry is naturally broken in several crystalline environments, such as at surfaces and interfaces, maximizing the influence of this effect on the electronic states of interest remains a challenge. Here we present a mechanism for realizing a much larger coupling of inversion-symmetry breaking to itinerant surface electrons than is typically achieved. The key element is a pronounced asymmetry of surface hopping energies-that is, a kinetic-energy-coupled inversion-symmetry breaking, the energy scale of which is a substantial fraction of the bandwidth. Using Spin- and angle-resolved photoemission spectroscopy, we demonstrate that such a strong inversion-symmetry breaking, when combined with Spin-orbit interactions, can mediate Rashba-like Spin Splittings that are much larger than would typically be expected. The energy scale of the inversion-symmetry breaking that we achieve is so large that the Spin Splitting in the CoO2- and RhO2-derived surface states of delafossite oxides becomes controlled by the full atomic Spin-orbit coupling of the 3d and 4d transition metals, resulting in some of the largest known Rashba-like Spin Splittings. The core structural building blocks that facilitate the bandwidth-scaled inversion-symmetry breaking are common to numerous materials. Our findings therefore provide opportunities for creating Spin-textured states and suggest routes to interfacial control of inversion-symmetry breaking in designer heterostructures of oxides and other material classes.
V Umansky - One of the best experts on this subject based on the ideXlab platform.
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radiation induced oscillatory magnetoresistance as a sensitive probe of the zero field Spin Splitting in high mobilitygaas alxga1 xasdevices
Physical Review B, 2004Co-Authors: R G Mani, J H Smet, K Von Klitzing, V Narayanamurti, W B Johnson, V UmanskyAbstract:We suggest an approach for characterizing the zero-field Spin Splitting of high mobility two-dimensional electron systems, when beats are not readily observable in the Shubnikov-de Haas effect. The zero-field Spin Splitting and the effective magnetic field seen in the reference frame of the electron are evaluated from a quantitative study of beats observed in radiation-induced magneto-resistance oscillations.
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radiation induced oscillatory magnetoresistance as a sensitive probe of the zero field Spin Splitting in high mobility gaas al x ga 1 x as devices
Physical Review B, 2004Co-Authors: R G Mani, J H Smet, K Von Klitzing, V Narayanamurti, W B Johnson, V UmanskyAbstract:We suggest an approach for characterizing the zero-field Spin Splitting of high mobility two-dimensional electron systems, when beats are not readily observable in the Shubnikov-de Haas effect. The zero-field Spin Splitting and the effective magnetic field seen in the reference frame of the electron are evaluated from a quantitative study of beats observed in radiation-induced magneto-resistance oscillations.
