Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userCurrent-driven Rashba Field in a Magnetic Quantum Well
132
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
In materials lacking inversion symmetry, the spin-orbit coupling enables the direct connection between the electrons spin and its linear momentum, a phenomenon called inverse spin galvanic effect. In magnetic materials, this effect promotes current-driven torques that can be used to control the magnetization direction electrically. In this work, we investigate the current-driven inverse spin galvanic effect in a quantum well consisting in a magnetic material embedded between dissimilar insulators. Assuming the presence of Rashba spin-orbit coupling at the interfaces, we investigate the nature of the non-equilibrium spin density and the influence of the quantum well parameters. We find that the torque is governed by the interplay between the number of states participating to the transport and their spin chirality, the penetration of the wave function into the tunnel barriers, and the strength of the Rashba term.
rate research
Read More
We demonstrate a spin pump to generate pure spin current of tunable intensity and polarization in the absence of charge current. The pumping functionality is achieved by means of an ac gate voltage that modulates the Rashba constant dynamically in a local region of a quantum channel with both static Rashba and Dresselhaus spin-orbit interactions. Spin-resolved Floquet scattering matrix is calculated to analyze the whole scattering process. Pumped spin current can be divided into spin-preserved transmission and spin-flip reflection parts. These two terms have opposite polarization of spin current and are competing with each other. Our proposed spin-based device can be utilized for non-magnetic control of spin flow by tuning the ac gate voltage and the driving frequency.
It is shown that the excitation of charge carriers by ac electric field with zero average driving leads to a direct electric current in quantum well structures. The current emerges for both linear and circular polarization of the ac electric field and depends on the field polarization and frequency. We present a micoscopic model and an analytical theory of such a nonlinear electron transport in quantum wells with structure inversion asymmetry. In such systems, dc current is induced by ac electric field which has both the in-plane and out-of-plane components. The ac field polarized in the interface plane gives rise to a direct current if the quantum well is subjected to an in-plane static magnetic field.
Magnetic skyrmionium can be used as a nanometer-scale non-volatile information carrier, which shows no skyrmion Hall effect due to its special structure carrying zero topological charge. Here, we report the static and dynamic properties of an isolated nanoscale skyrmionium in a frustrated magnetic monolayer, where the skyrmionium is stabilized by competing interactions. The frustrated skyrmionium has a size of about $10$ nm, which can be further reduced by tuning perpendicular magnetic anisotropy or magnetic field. It is found that the nanoscale skyrmionium driven by the damping-like spin-orbit torque shows directional motion with a favored Bloch-type helicity. A small driving current or magnetic field can lead to the transformation of an unstable Neel-type skyrmionium to a metastable Bloch-type skyrmionium. A large driving current may result in the distortion and collapse of the Bloch-type skyrmionium. Our results are useful for the understanding of frustrated skyrmionium physics, which also provide guidelines for the design of spintronic devices based on topological spin textures.
We investigate the double-layer electron system in a parabolic quantum well at filling factor $ u=2$ in a tilted magnetic field using capacitance spectroscopy. The competition between two ground states is found at the Zeeman splitting appreciably smaller than the symmetric-antisymmetric splitting. Although at the transition point the system breaks up into domains of the two competing states, the activation energy turns out to be finite, signaling the occurrence of a new insulator-insulator quantum phase transition. We interpret the obtained results in terms of a predicted canted antiferromagnetic phase.
We study the role of different orientations of an applied magnetic field as well as the interplay of structural asymmetries on the characteristics of eigenstates in a quantum ring system. We use a nearly analytical model description of the quantum ring, which allows for a thorough study of elliptical deformations and their influence on the spin content and Berry phase of different quantum states. The diamagnetic shift and Zeeman interaction compete with the Rashba spin-orbit interaction, induced by confinement asymmetries and external electric fields, to change spin textures of the different states. Smooth variations in the Berry phase are observed for symmetric quantum rings as function of applied magnetic fields. Interestingly, we find that asymmetries induce nontrivial Berry phases, suggesting that defects in realistic structures would facilitate the observation of geometric phases.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
