Giant injection magnetoresistance in the heterostructure gallium arsenide/granular film with cobalt nanoparticles

Lutsev, L. V.; Stognij, A. I.; Новицкий, Н. Н.; Stashkevich, A. A.

doi:10.1016/j.jmmm.2005.10.138

Cited by 17 publications

(15 citation statements)

References 10 publications

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“…5. Extremely large magnetoresistance can be achieved by use magnetic-field-dependent avalanche breakdown phenomena [35,36,37,38,39,40,41,42,43]. Values of the magnetoresistance effect based on the avalanche breakdown reach 10 5 % in the Au / semi-insulating GaAs Schottky diode at room temperature [37].…”

Section: Introductionmentioning

confidence: 99%

Giant magnetoresistance in semiconductor/granular film heterostructures with cobalt nanoparticles

2009

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We have studied the electron transport in SiO 2 (Co)/GaAs and SiO 2 (Co)/Si heterostructures, where the SiO 2 (Co) structure is the granular SiO 2 film with Co nanoparticles. In SiO 2 (Co)/GaAs heterostructures giant magnetoresistance effect is observed. The effect has positive values, is expressed, when electrons are injected from the granular film into the GaAs semiconductor, and has the temperature-peak type character. The temperature location of the effect depends on the Co concentration and can be shifted by the applied electrical field. For the SiO 2 (Co)/GaAs heterostructure with 71 at.% Co the magnetoresistance reaches 1000 (10 5 %) at room temperature. On the contrary, for SiO 2 (Co)/Si heterostructures magnetoresistance values are very small (4%) and for SiO 2 (Co) films the magnetoresistance has an opposite value. High values of the magnetoresistance effect in SiO 2 (Co)/GaAs heterostructures have been explained by magnetic-field-controlled process of impact ionization in the vicinity of the spin-dependent potential barrier formed in the semiconductor near the interface. Kinetic energy of electrons, which pass through the barrier and trigger the avalanche process, is reduced by the applied magnetic field. This electron energy suppression postpones the onset of the impact ionization to higher electric fields and results in the giant magnetoresistance. The spin-dependent potential barrier is due to the exchange interaction between electrons in the accumulation electron layer in the semiconductor and d-electrons of Co. Existence of spin-polarized localized electron states in the accumulation layer results in the temperature-peak type character of the barrier and the magnetoresistance effect. Spin injector and spin-valve structure on the base of ferromagnet / semiconductor heterostructures with quantum wells with spin-polarized localized electrons in the semiconductor at the interface are considered.

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Section: Introductionmentioning

confidence: 99%

Giant magnetoresistance in semiconductor/granular film heterostructures with cobalt nanoparticles

2009

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“…The experimental temperature dependence of the IMR coefficient for the SiO 2 (Co)/GaAs structure with x Co = 60 at.% has a maximum at T = 280 K (figure 9) [22,23]. As a function of T , the experimental temperature dependence is proportional to the calculated temperature dependence of the potential barrier height W for the SC/granular film heterostructure with the difference of chemical potentials µ = 0.23 eV ( figure 5).…”

Section: Injection Magnetoresistance In Semiconductor/granular Film Hmentioning

confidence: 96%

“…A new phenomenon, injection magnetoresistance, has been observed in GaAs/SiO 2 granular film with Co nanoparticles [22,23]. The injection magnetoresistance is the suppression of the electron injection from the granular film into GaAs induced by the magnetic field.…”

Section: Injection Magnetoresistance In Semiconductor/granular Film Hmentioning

confidence: 99%

“…The observed injection magnetoresistance effect can be explained by the developed theory. For the explanation it is essential that (1) the domain structure is experimentally observed in the granular film [23] and (2) the potential barrier is formed in the accumulation electron layer in the SC at the distance r 0 from the interface plane ( figure 3). Due to the RKKY interaction between d electrons of neighbouring Co particles, which are close to the interface, and electrons of the accumulation layer in the SC, ferromagnetic metal particles with electrons of the accumulation layer form a ferromagnetic layer ( figure 8).…”

Section: Injection Magnetoresistance In Semiconductor/granular Film Hmentioning

confidence: 99%

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Potential barrier for spin-polarized electrons induced by the exchange interaction at the interface in the ferromagnet/semiconductor heterostructure

Lutsev¹

2006

J. Phys.: Condens. Matter

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We have calculated the exchange interaction between electrons in the accumulation electron layer in the semiconductor near the interface and electrons in the ferromagnet in the ferromagnet/semiconductor heterostructure. It is found that the exchange interaction forms the potential barrier for spin-polarized electrons. The barrier height strongly depends on the difference of chemical potentials between the semiconductor and the ferromagnet. The maximum of the potential barrier height on the temperature dependence is due to the existence of localized electron states in the accumulation layer. In the framework of the developed theoretical model, the injection magnetoresistance effect observed in semiconductor/granular film heterostructures with ferromagnetic metal nanoparticles is explained. A spin filter on the base of granular film/semiconductor/granular film heterostructures operated at room temperature is proposed.

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“…In silicon dioxide heterostructures with cobalt nanoparticles grown on GaAs substrates, the injection magnetoresistance reaches 5200% at room temperature [17,18]. These magnetoresistance values are two orders of magnitude higher than maximum magnetoresistance values, now achieved in multilayers, magnetic tunnel structures and granular films.…”

Section: Introductionmentioning

confidence: 94%

Electron spin resonance properties of semiconductor/granular film heterostructures with cobalt nanoparticles in millimeter waveband

Khodzitskiy¹,

Lutsev²,

Tarapov³

et al. 2008

Journal of Magnetism and Magnetic Materials

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Giant injection magnetoresistance in the heterostructure gallium arsenide/granular film with cobalt nanoparticles

Cited by 17 publications

References 10 publications

Giant magnetoresistance in semiconductor/granular film heterostructures with cobalt nanoparticles

Giant magnetoresistance in semiconductor/granular film heterostructures with cobalt nanoparticles

Potential barrier for spin-polarized electrons induced by the exchange interaction at the interface in the ferromagnet/semiconductor heterostructure

Electron spin resonance properties of semiconductor/granular film heterostructures with cobalt nanoparticles in millimeter waveband

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