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(Color online) Temperature dependence of magnetization of MTJ structures with (a) 3-, (b) 6-, and (c) -thick spacer, respectively. and stand for Curie temperatures of the bottom and the top (Ga,Mn)As layer, respectively. Applied magnetic field was aligned along the ⟨110⟩ directions as labeled in panel (a). Data were taken at remanence state, i.e, saturating the sample first and then demagnetizing to . The inset in (b) shows of the two layers as a function of the spacer thickness.
Planar Hall effect data taken at at several values of , where denotes the angle between the current direction (i.e.,[1-10]) and the applied magnetic field.
(Color online) (a) Schematic diagram of the model of PHE in a MTJ structure. The cross section perpendicular to the current direction is regarded as a network consisting of batteries ( and ), and resistors (, , and ). Here, and are Hall voltages generated by microscopically local regions in the top and bottom layers, respectively, and are the corresponding resistances of these local regions, and is the tunneling resistance at such local region. (b) and (c) are PHE and MR curves of the sample with -thick spacer when the magnetic field makes an angle of 30° with the current direction, respectively. (d) and (e) are PHE and MR curves of the same sample when , respectively. Shaded areas illustrate each electrical state demonstrated. Red arrows in all panels stand for the magnetization of the top (soft) layer, while black arrows for the bottom (hard) layer . The directions of the arrows reflect the directions of the magnetizations relative to the direction of the current.
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