We report the epitaxial growth of high-quality Al_(0.8)Ga_(0.2)Sb/InAs/Al_(0.8)Ga_(0.2)Sb quantum well films characterized by high carrier mobility and strong spin-orbit coupling.By appropriately optimizing the Al-to-...We report the epitaxial growth of high-quality Al_(0.8)Ga_(0.2)Sb/InAs/Al_(0.8)Ga_(0.2)Sb quantum well films characterized by high carrier mobility and strong spin-orbit coupling.By appropriately optimizing the Al-to-Ga ratio in the AlGaSb barrier layer,the quantum confinement of the heterostructure is significantly enhanced.Alongside a giant magnetoresistance ratio of 3.65×10^(5)%,the two-carrier transport model from Hall measurements reveals an ultra-high electron mobility of 7.18×10^(5)cm^(2)·V^(-1)·s^(-1)at low temperatures.Meanwhile,pronounced Shubnikov-de Haas(SdH)quantum oscillations persist up to 30 K,and their single-frequency feature indicates a well-defined Fermi surface without subband mixing in the two-dimensional electron gas channel.Moreover,the large effective g-factor and tilted-field-induced orbital effect lead to the observation of split SdH peaks at large magnetic fields.Our results validate that AlGaSb/InAs quantum well heterostructures are suitable candidates for constructing energy-efficient topological spintronic devices.展开更多
To suppress the resistivity positive temperature coefficient(PTC)effect of ethylene-butyl acrylate copolymer(EBA)-based semi-conductive shielding layer and the injection of charge carriers to insulation layer,the pola...To suppress the resistivity positive temperature coefficient(PTC)effect of ethylene-butyl acrylate copolymer(EBA)-based semi-conductive shielding layer and the injection of charge carriers to insulation layer,the polar molecule maleic anhydride(MAH)is grafted onto EBA macromolecules by melt blending and thermal grafting.The resistivity temperature stability of the grafted semi-conductive composites,as well as the space charge distribution and direct current(DC)breakdown characteristics of cross-linked polyethylene(XLPE)insulation using the composites as the electrode is investigated.The results show that MAH grafting can significantly reduce the volume resistivity of semi-conductive composites,especially at a higher temperature,to suppress the PTC effect.And,the grafted semi-conductive composites can prevent the injection of charge carriers to XLPE insulation from the semi-conductive electrode to improve the space charge distribution and DC breakdown strength of XLPE insulation.The polar anhydride groups in the grafted MAH can enhance the interaction between EBA macromolecular chains and between EBA macromolecular chains and carbon black(CB)to improve the dispersion of CB in EBA matrix and the stability of the internal conductive network at the high temperature,improving the properties of EBA-based semi-conductive shielding layer and DC electrical properties of XLPE insulation layer.展开更多
基金supported by R&D the National Key Program of China(Grant No.2021YFA0715503)the Major Project ofShanghai Municipal Science and Technology(Grant No.2018SHZDZX02)the ShanghaiTech Mate rial Device and Soft Matter Nano-fabrication Labs(No.SMN180827).
文摘We report the epitaxial growth of high-quality Al_(0.8)Ga_(0.2)Sb/InAs/Al_(0.8)Ga_(0.2)Sb quantum well films characterized by high carrier mobility and strong spin-orbit coupling.By appropriately optimizing the Al-to-Ga ratio in the AlGaSb barrier layer,the quantum confinement of the heterostructure is significantly enhanced.Alongside a giant magnetoresistance ratio of 3.65×10^(5)%,the two-carrier transport model from Hall measurements reveals an ultra-high electron mobility of 7.18×10^(5)cm^(2)·V^(-1)·s^(-1)at low temperatures.Meanwhile,pronounced Shubnikov-de Haas(SdH)quantum oscillations persist up to 30 K,and their single-frequency feature indicates a well-defined Fermi surface without subband mixing in the two-dimensional electron gas channel.Moreover,the large effective g-factor and tilted-field-induced orbital effect lead to the observation of split SdH peaks at large magnetic fields.Our results validate that AlGaSb/InAs quantum well heterostructures are suitable candidates for constructing energy-efficient topological spintronic devices.
基金National Natural Science Foundation of China,Grant/Award Number:U20A20307Key Laboratory of Engineering Dielectrics and Its Application(Harbin University of Science and Technology),Ministry of Education,Grant/Award Number:KFM202102。
文摘To suppress the resistivity positive temperature coefficient(PTC)effect of ethylene-butyl acrylate copolymer(EBA)-based semi-conductive shielding layer and the injection of charge carriers to insulation layer,the polar molecule maleic anhydride(MAH)is grafted onto EBA macromolecules by melt blending and thermal grafting.The resistivity temperature stability of the grafted semi-conductive composites,as well as the space charge distribution and direct current(DC)breakdown characteristics of cross-linked polyethylene(XLPE)insulation using the composites as the electrode is investigated.The results show that MAH grafting can significantly reduce the volume resistivity of semi-conductive composites,especially at a higher temperature,to suppress the PTC effect.And,the grafted semi-conductive composites can prevent the injection of charge carriers to XLPE insulation from the semi-conductive electrode to improve the space charge distribution and DC breakdown strength of XLPE insulation.The polar anhydride groups in the grafted MAH can enhance the interaction between EBA macromolecular chains and between EBA macromolecular chains and carbon black(CB)to improve the dispersion of CB in EBA matrix and the stability of the internal conductive network at the high temperature,improving the properties of EBA-based semi-conductive shielding layer and DC electrical properties of XLPE insulation layer.
