Naslov
Spin-dependent transport in single and double barrier tunnel junctions based on ferromagnetic semiconductors GaMnAs

Autori
Mattana, Richard ; George, Jean-Marie ; Jaffres, Henry ; N Guyen Van Dau, Frederic ; Fert, Albert ; Lepine, B. ; Guivarch, A. ; Jezequel, G. ; Hamzić, Amir ; Basletić, Mario ; Tafra, Emil

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
47th Annual Conference on Magnetism & Magnetic Materials MMM'02 / - Tampa (FL), 2002

Skup
47th Annual Conference on Magnetism & Magnetic Materials

Mjesto i datum
Tampa (FL), Sjedinjene Američke Države, 11.11.2002. - 15.11.2002

Vrsta sudjelovanja
Plenarno

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
spintronics; magnetic semiconductors; tunnel magnetoresistance

Sažetak
For spin injection into semiconductors, magnetic semiconductors are an alternative to ferromagnetic metals, with the advantage that the difficulties resulting from the conductivity mismatch between metal and semiconductor can be avoided. On the other hand, magnetic tunnel junctions with magnetic semiconductor electrodes can be used to test spin injection since the existence of magnetoresistance (TMR) is a signature of the transmission of spin polarized carriers between the electrodes. We have fabricated single and double barrier magnetic tunnel junctions with GaMnAs electrodes by a low temperature molecular beam epitaxy procedure. The two magnetic electrodes (Ga_(1-x)Mn_xAs)) are separated by thin AlAs (1.7nm) tunnel barrier (single barrier MTJ) or by a AlAs(1.7nm)/GaAs(5nm)/AlAs(1.7nm) trilayer (double barrier MTJ). Antiparallel arrangement of the ferromagnetic electrodes at low field is obtained by playing with the thickness and manganese concentration in the GaMnAs layers to obtain different coercive fields. GaAs layers have been inserted between electrodes and tunnel barrier in order to avoid the diffusion of the manganese into the tunnel barrier. We observe large TMR effects, 38% at low field and 650% at 5 T in the single junction after progressive saturation of the electrode magnetization. The existence of similar large MR ratios in the double junction is a new and interesting effect, never observed in metallic double junctions when the intermediate electrode is nonmagnetic. This can be ascribed by the non-relaxed spin splitting of the chemical potential predicted for a semiconductor intermediate electrode.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

POVEZANOST RADA