Inverted current-driven switching in Fe(Cr)/Cr/Fe(Cr) nanopillars

Abstract

From both theory and experiment, scattering of minority electrons is expected to be weaker than scattering of majority electrons in both dilute Fe(Cr) alloys and at Fe(Cr)/Cr interfaces. We show that Fe(Cr)/Cr/Fe(Cr) trilayer nanopillars display a normal magnetoresistance--i.e., largest resistance at low magnetic fields and smallest at high fields, but an inverted current-driven switching--i.e., positive current flowing from the fixed to the reversing layer switches the trilayer from higher to lower resistance, and negative current switches it from lower to higher.Comment: 3 pages, 3 figs., accepted for J. Magn. Magn. Mat., MMM/Intermag Conf. 200

Controlled Normal and Inverse Current-Induced Magnetization Switching and Magnetoresistance in Magnetic Nanopillars

“…Since F1 and F2 are the same alloy, FeCr30-Cr6-FeCr3:5 nanopillars should give normal MR [21,22]. Figure 2 shows that they do and also give inverse CIMS; see also [23]. The changes in dV=dI vs I or H are smaller than for Py-Cu-Py, due to spin-memory loss in the Cr6 layer [24] and smaller scattering anisotropy of FeCr [22].…”

“…We present CIMS experiments exploiting the possibility of inverting the spin anisotropy by doping F1, F2, or both together, with an impurity (Cr) that scatters majority spin electrons more strongly [21][22][23][24][25][26][27][28]. We thus show, for the first time, that inversion of the spin anisotropy can invert the CIMS direction, i.e., invert the signs of I for AP to P and P to AP transitions.…”

Co2FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

“…Looking at the spin resolved density of states for Fe 16 and Co 2 FeAl, 17 it is obvious that the majority spins dominate within the energy range of the gap in the minority band of Co 2 FeAl, which is larger than the voltage applied and hence will not result in a negative TMR effect. However, the question arises whether this negative TMR effect could be related to spin transfer torque (STT) as is reported by AlHajDarwish et al 18 for Fe(Cr) / Cr /Fe(Cr) nanopillars. The current densities applied in our transport measurements are much smaller and differ by a factor of at least 1.5 x 10 −3 from the current densities they have been using.…”