Large magnetoresistance in Co∕Ni∕Co ferromagnetic single electron transistors

Abstract

We report on magnetotransport investigations of nano-scaled ferromagnetic Co/Ni/Co single electron transistors. As a result of reduced size, the devices exhibit single electron transistor characteristics at 4.2K. Magnetotransport measurements carried out at 1.8K reveal tunneling magnetoresistance (TMR) traces with negative coercive fields, which we interpret in terms of a switching mechanism driven by the shape anisotropy of the central wire-like Ni island. A large TMR of about 18% is observed within a finite source-drain bias regime. The TMR decreases rapidly with increasing bias, which we tentatively attribute to excitation of magnons in the central island.

Magnetic field effect on electron spin dynamics in (110) GaAs quantum wells

“…In a simple picture, the mechanism is as follows. If B = 0, the photogenerated electron spin, initially oriented along z (the growth axis), can be decomposed into its projectionsS z andS y along the eigen axesz (lying (11) and (8,9) respectively.…”

“…The electron spin dynamics in these three samples have been studied by time resolved Kerr rotation (TRKR) experiments [8]. The samples were excited at near normal incidence with degenerate pump and delayed probe pulses by a Ti:sapphire laser (pulse width 100 fs and repetition frequency 76 MHz).…”

“…As a consequence, the electron spin relaxation tensor varies strongly if the quantum wells are grown on (001), (110) or (111) oriented substrates. The interplay between the BIA and SIA terms has been studied experimentally and theoretically by several groups in recent years [5][6][7][8][9][10][11][12][13][14].…”

Magneto-optical effects enhancement in DMS layers utilizing 1-D photonic crystal

“…Our approach is different from the one developed in, e.g., Refs. [10][11][12][13], where the enhancement of magnetooptical Faraday effect was obtained by enclosing a DMS layer within a photonic cavity made of two DBR mirrors, or e.g., Ref. [14], where in order to enhance the MOKE, a layer with single-domain nanomagnets was placed under a dielectric multilayer.…”

“…They affect the propagation of the electromagnetic wave similarly as the periodic potential in a crystal affects the motion of electrons and exhibit, in particular, a forbidden gap in frequency domain. [8] Although it was highlighted in a number of works [9][10][11][12][13][14] that combining the advantages offered by both domains: DMS and photonics, may enforce a new capabilities in current and future devices, until recently DMS and photonics paved their way in the modern physics mostly separately.…”