Spin filter effect at room temperature in GaN/GaMnN ferromagnetic resonant tunnelling diode

Abstract

We have investigated the spin current polarization without the external magnetic field in the resonant tunneling diode with the emitter and quantum well layers made from the ferromagnetic GaMnN. For this purpose we have applied the self-consistent Wigner-Poisson method and studied the spin-polarizing effect of the parallel and antiparallel alignment of the magnetization in the ferromagnetic layers. The results of our calculations show that the antiparallel magnetization is much more advantageous for the spin filter operation and leads to the full spin current polarization at low temperatures and 35 % spin polarization of the current at room temperature.The progress in homo-and heteroepitaxy of dilute magnetic semiconductors 1-8 (DMS's) during the past decade allows to fabricate spintronic nanodevices, in which the spin polarization of the current can be controlled by the magnetic or electric field. The spin filter effect in a resonant tunneling diode (RTD) with paramagnetic quantum well embedded in II-VI DMS (ZnMnSe) was studied theoretically 9-11 and experimentally demonstrated by Slobodskyy et al. 12 For the paramagnetic RTD, in the presence of the external magnetic field, the exchange interaction between the conduction band electrons and the Mn 2+ ions leads the giant Zeeman splitting 13 of the quasi-bound state in the paramagnetic quantum-well. This splitting causes that the resonance conditions for the spin up and spin down electrons are satisfied for different bias voltages leading to the separation of the spin current components and consequently to the spin polarization of the current. The spin filter effect in the paramagnetic RTD is limited to very low temperature and requires the high external magnetic field. 12,13 These restrictions cause that more interest is directed towards the application of the ferromagnetic III-V semiconductors, especially those with high Curie temperature, e.g. GaMnAs 8,14-16 or GaMnN. 17,18 Ohno et al. 19 experimentally studied the ferromagnetic RTD based on GaMnAs in which the spin splitting was observed without external magnetic field but it still requires low temperature. Hovewer, the recent experiments reported that GaMnN can exhibit the ferromagnetic properties above room temperature 20-22 at which the exchange splitting of the conduction band is about few tens of meV 23 and remains in the limit of thin layer of a few nanometer width. 24 Although the ferromagnetism in GaMnN is still unresolved theoretical problem, the spin filter effect in the RTD's based on GaMnN is a subject of research carried out by many groups. Recently, Li et al. 25 have theoretically investigated the ferromagnetic RTD consisted of the InGaN quantum well between two GaMnN barriers. In Ref. 25 the spin polarization of the current without magnetic field has been predicted at low temperature but at room temperature it has been reduced to only 8 %. Another way to obtain the spin polarization of the current at room temperature was proposed by Qui el at. 26 who stated that the δ doping of the GaN quant...

Interplay between resonant tunneling and spin precession oscillations in all-electric all-semiconductor spin transistors

“…Another important issue for future works is the role of electron-electron interactions, which may lead to instabilities and hysteretic curves in double barrier systems [65]. Furthermore, magnetically doped resonant tunneling devices are shown to be quite sensitive to external magnetic fields [66][67][68]. In the presence of a spin-orbit coupling beating patterns are predicted to occur in double-barrier resonant tunneling structures [69].…”

Transition from positive to negative magnetoresistance induced by a constriction in semiconductor nanowire

“…It can operate as a spin filter 51,52 in which the spin filtering operation results from the joint effect of the constriction and spin Zeeman effect controlled by the magnetic field. This operation is similar to the operation of the quantum point contacts.…”

Effect of the inter-subband spin-orbit interaction on the spin transistor operation

“…The lower panels in Fig. 3 depict the partial spin density distributions: (I) s 11 z and (II) s 12 z correspond to the spin density distribution in the first and second subband, respectively, if the electron with spin up is injected into the first subband, while s 21 z (III) and s 22 z (IV) correspond to the spin density distribution in the first and second subband, if the electron with spin up is injected into the second subband. These partial spin density distributions give us information not only about the spin dynamics in the considered subband but also about the spin behavior due to the inter-subband transitions.…”

“…Therefore, the basic condition which has to be meet in the experimental setup of the spin-FET is the spin injection (detection) nearly equals to 100% -the ratio G on /G of f = 10 5 , adequate for the modern electronics, requires P S = P D = 99.9995%. 9 This requirement can be satisfied only by the use of the semiconductor spin filters such as magnetic resonant tunneling diodes 10,11 or quantum point contacts (QPC) with the lateral Rashba SO interaction. [12][13][14][15] The latter have been successfully used as the spin injector and detector in the recent experiment, 16,17 in which about 10 5 times greater conductance oscillations have been observed as compared to the conventional spin-FET based on ferromagnets.…”