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Precision mapping the topological bands of 2D spin-orbit coupling with microwave spin-injection spectroscopy
摘要： To investigate the band structure is one of the key approaches to study the fundamental properties of a novel material. We report here the precision band mapping of a 2-dimensional (2D) spin-orbit (SO) coupling in an optical lattice. By applying the microwave spin-injection spectroscopy, the band structure and spin-polarization distribution are achieved simultaneously. The band topology is also addressed with observing the band gap close and re-open at the Dirac points. Furthermore, the lattice depth and the Raman coupling strength are precisely calibrated with relative errors in the order of 10?3. Our approach could also be applied for exploring the exotic topological phases with even higher dimensional system.
关键词： Topological band,Microwave spin-injection spectroscopy,Spin polarization,Topological phase transition,2D spin-orbit coupling
更新于2025-09-23 15:23:52
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Room temperature spin injection into SiC via Schottky barrier
摘要： Electrical spin injection into and spin extraction from a wide-bandgap semiconductor SiC at room temperature were demonstrated via Schottky junctions. The spin relaxation time of SiC could reach 300 ps, overwhelming that of Si with similar carrier density due to the smaller atomic number. We also found that there existed two channels in SiC/CoFeB Schottky junctions for spin relaxation, one from bulk SiC and the other from interfacial defect states within the barrier whose spin relaxation times were about 1 ns. The bias condition controlled transport channels via bulk or defect states within the barrier and then affected the effective spin relaxation process. Realization of spin injection into SiC shed light on spintronics of wide-bandgap semiconductors such as spin-resolved blue light emitting diodes and high power/temperature spintronics.
关键词： spintronics,SiC,spin injection,Schottky barrier,wide-bandgap semiconductor
更新于2025-09-23 15:21:21
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Polarisation responses of a solitary and optically injected vertical cavity spin laser
摘要： The polarisation properties of a quantum well spin – vertical cavity surface emitting laser (spin – VCSEL), both without injection and with variable polarisation optical injection, are investigated experimentally and compared with the spin flip model (SFM). Without injection, we demonstrate two distinct types of VCSEL-pump response depending on the signs of the linewidth enhancement factor, birefringence and dichroism: firstly where the pump and VCSEL have the same sign of the ellipticity, and secondly where the VCSEL ellipticity, accompanied by the linear polarisation, switches sign. We show that by controlling the injected power, ellipticity or linear angle, near circular polarisation can be obtained. These responses both give insight into the electro-optical injected spin-VCSEL system, and have practical implications for the use of spin VCSELs in unique applications exploiting the ellipticity degree of freedom.
关键词： VCSEL,polarization,spin,injection
更新于2025-09-11 14:15:04
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Efficient spin injection into graphene through trilayer hBN tunnel barriers
摘要： We characterize the spin injection into bilayer graphene fully encapsulated in hexagonal boron nitride (hBN) including a trilayer (3L) hexagonal boron nitride (hBN) tunnel barrier. As a function of the DC bias, the differential spin injection polarization is found to rise to (cid:1)60% at (cid:1)250 mV DC bias voltage. We measure a DC spin polarization of (cid:1) 50%, 30% higher compared to 2L-hBN. The large polarization is con?rmed by local, two terminal spin transport measurements up to room temperature. We observe comparable differential spin injection ef?ciencies from Co/2L-hBN and Co/3L-hBN into graphene and conclude that the possible exchange interaction between cobalt and graphene is likely not the origin of the bias dependence. Furthermore, our results show that local gating arising from the applied DC bias is not responsible for the DC bias dependence. Carrier density dependent measurements of the spin injection ef?ciency are discussed, where we ?nd no signi?cant modulation of the differential spin injection polarization. We also address the bias dependence of the injection of in-plane and out-of-plane spins and conclude that the spin injection polarization is isotropic and does not depend on the applied bias.
关键词： spin polarization,hBN tunnel barriers,DC bias,graphene,spin injection
更新于2025-09-10 09:29:36