We show that the dissipationless spin current in the ground state of the Rashba model gives rise to a reactive coupling between the spin and charge propagation, which is formally identical to the coupling between the electric and the magnetic fields in the 2 + 1 dimensional Maxwell equation. This analogy leads to a remarkable prediction that a density packet can spontaneously split into two counter propagation packets, each carrying the opposite spins. In a certain parameter regime, the coupled spin and charge wave propagates like a transverse "photon". We propose both optical and purely electronic experiments to detect this effect. 72.15. Gd
An innovative tunable and polarization-insensitive 1.6–8 GHz frequency selective surface (FSS) absorber was investigated in this study. The proposed FSS, which is in 4-axial symmetrical form, includes a novel array of PIN diodes with biasing lines including inductors. A gradually reduced equivalent resistor of PIN diodes can be achieved with increasing DC voltage, which characterizes tunable, multi-resonance absorption peaks. Via this simplified design, small value resistor and equivalent capacitance of the gap between patterns can improve the absorber’s performance in low frequencies; an active tunable absorber can be realized in a broad frequency range by employing adjustable devices. Changing the working state of the PIN diode allows the user to obtain strong absorption within the desired frequency. We analyzed the performance of the proposed absorber and found that it indeed shows very favorable absorption performance in low frequency (−10 dB in 1.6−4.3 GHz) and wideband (−8 dB in 4.3−5.4 GHz and −10 dB in 5.4−8.0 GHz) conditions. Calculation and simulation results also illustrated that the absorber is entirely polarization-insensitive.
We present time-resolved x-ray images with 30 nm spatial and 70 ps temporal resolution, which reveal details of the spatially resolved magnetization evolution in nanoscale samples of various dimensions during reversible spin-torque switching processes. Our data in conjunction with micromagnetic simulations suggest a simple unified picture of magnetic switching based on the motion of a magnetic vortex. With decreasing size of the magnetic element the path of the vortex core moves from inside to outside of the nanoelement, and the switching process evolves from a curled nonuniform to an increasingly uniform mode.
A novel tunable frequency selective surface (FSS) with dual-degrees of freedom (DOF) is presented, and firstly applied to broadband absorber. Based on a simple prototype unit cell resonator, an approach for achieving multi-resonances is studied. A unit cell pattern with gradient edges is discussed, and variable resistor and variable capacitor are introduced to fully utilize its characteristic of multi-resonances. Bias line is designed to provide bias voltage respectively for two variable devices and provide two operational DOF for FSS. Simulation and measurement results both show that the tunable FSS absorber with dual-DOF has wideband absorption with the reflectivity below -10 dB in 1-5 GHz and with a total thickness of about 10 mm.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.