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(a) TMR ratio as a function of the magnetic field, where two coercive fields are clearly observed. (b) TMR as a function of temperature at constant current (1 μA). The TMR disappears at about 200 K due to a diminished TC in the insulator-ferromagnet interface. (c) IV characteristics of both magnetic states at 5 K. (d) TMR dependence on voltage bias obtained from the curves in (c).
(a) Noise power spectrum in a MTJ at different bias voltages in saturated state (600 Oe) and at 5 K. The dashed (orange) line is the linear curve for a pure 1/f noise. (b) Normalized noise as a function of temperature at two different frequencies, fixed current bias and in the saturated state (600 Oe).
Normalized noise (dot-line curve) as a function of applied field at low frequency (1-20 Hz) (a) at 5 K and (b) at 165 K. In both cases, the right axis shows the TMR (line curve) curve acquired in the same experiment. The dependence of the noise indicates that close to the P to AP transitions there is an enhancement of the noise due to magnetic noise.
Comparison between α parameters obtained in MgO-based MTJs and the measurements studied here for various RA products. The data from Ref. 20 come from epitaxial Fe/MgO/Fe MTJs and Refs. 19 and 21 from polycrystalline and annealed Fe/MgO/Fe MTJs.
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