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[Co.sub.40][Fe.sub.40][B.sub.20]/MgO single and double barrier magnetic tunnel junctions (MTJs) are grown by using target-facing-target sputtering for MgO barriers and conventional dc magnetron sputtering for [C.sub.40][Fe.sub.40][B.sub.20] ferromagnetic electrodes. Large tunnel magnetoresistance (TMR) ratios are obtained after postdeposition annealing and lower TMR ratio for double barrier MTJs is attributed to the amorphous nature of the middle [Co.sub.40][Fe.sub.40][B.sub.20] free layer.

Magnetic tunneling junctions with Co 40 Fe 40 B 20 /Co 70.5 Fe 4.5 Si 15 B 10 composite free layer have been fabricated and annealed at different temperatures to obtain the highest tunneling magnetoresistance. The field and temperature dependences of the low frequency noise have been measured to understand the origin of noise. The random telegraph noise has been observed at low magnetic field, and the corresponding fluctuating moment is estimated to be 4.8×10 5 μ B with an effective area of 240 nm 2 . The dependence of noise on temperature was coincident with the thermally activated kinetics model above 30 K while it deviated from this model below 30 K. Studying the origin of the low frequency noise is helpful to reduce the noise level in MTJs. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate that high-quality magnetic tunnel junctions with Co40Fe40B20 electrodes and crystalline MgO barriers, which show a 230% tunneling magnetoresistance ratio at room temperature, can be successfully fabricated by using a target-facing-target sputtering technique and present the results on the change of barrier asymmetry after the annealing at different temperatures. Bias voltage dependence of magnetoresistance ratio for Co40Fe40B20/MgO magnetic tunnel junctions is highly asymmetrical in the as-deposited states and becomes more symmetrical after magnetic annealing. It also exhibits a shift of the tunneling magnetoresistance maximum to a positive bias voltage under the low-temperature annealing. [Copyright &y& Elsevier]

Abstract: La0.67Ca0.33MnO3 (LCMO)/La0.67Sr0.33CoO3 (LSCO)/LCMO trilayer films are fabricated on single-crystal substrates NdGaO3 (110) and the interlayer coupling are investigated. Compared with LCMO single layer, sandwiches showed the enhanced metal–insulator transition temperature of LCMO layers. The magnetoresistance is dependent on spacer thickness and the peak value dramatically decreases when LSCO layer is thick enough because of shorting by the LSCO layer. The magnetic coercivity H C shows a nonmonotonic behavior with changing spacer layer thickness and the waist-like hysteresis indicates that there is an indirect exchange coupling between the top and bottom LCMO layers across the spacer layer. [Copyright &y& Elsevier]

Abstract: Magnetic coercivity and anisotropy have been investigated in amorphous Co50Fe50 t/Tb t multilayers with perpendicular anisotropy. The thin CoFe layer does not crystallize when sandwiched between Tb layers. The saturation magnetization M s (~106 A/m) and perpendicular magnetic anisotropy constant K u (~105 J/m3) combined with low coercivity μ0 H c (10–102 mT) have been obtained. These magnetic properties can be tuned. These amorphous multilayers could be designed to suit specific spintronic applications. [Copyright &y& Elsevier]

Abstract: Perpendicular magnetic anisotropy (PMA) has been investigated in ultrathin (CoFe [0.2]nm/Pt [0.2]nm) n multilayers. The Pt layers show an fcc crystal structure with a preferred [111] orientation. The multilayers with n=3, 4 show PMA in the as-grown state, which can be enhanced by thermal annealing. However, no PMA is observed in the as-grown state with higher repetitions (n>&=5), although it is observed after thermal annealing. For 1=&