• Co/ZnO and Co/ZnAlO films were prepared by depositing ultrathin cobalt layers and semiconductor layers on glass substrates at room temperature. The films consist of metallic Co particles, semiconductor matrix, and an interfacial magnetic semiconductor with the substitution of Co2+ for Zn 2+ in the ZnO lattice at the interface between Co particles and the semiconductor matrix. Large room temperature negative tunneling magnetoresistance was observed in the films. In addition, the magnetism and magnetoresistance were obviously enhanced by adding aluminum to the ZnO, and in one Co/ZnAlO sample, the room temperature negative magnetoresistance value reaches -12.3% at 18 kOe (compared with -8.4% of the corresponding Co/ZnO film) and the spin polarization of the tunneling electrons is about 37.5% which is characteristic of metallic Co. This enhancement of the tunneling spin polarization has been ascribed to the tunneling through an interfacial magnetic semiconductor, which causes the robust spin injection from cobalt metal into the semiconductors at room temperature resulting from the spin filter effect of the interfacial magnetic semiconductors.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

Nyckelord

interfacial magnetic semiconductors

magnetoresistance

spin filtering

spin polarization

sputtering

Negative magneto-resistance

Room temperature magnetoresistance

Semiconductor layers

Semiconductor matrices

Spin filter effect

Tunneling magnetoresistance

Tunneling spin polarization

Interfaces (materials)

Magnetic semiconductors

Substrates

Tunnelling magnetoresistance

Ultrathin films

Zinc oxide

Cobalt

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