Influence of capping layer on the current-induced magnetization switching in magnetic nanopillars

Abstract

Taking into account the thermal effect, we verify that the strong spin relaxation in the capping layer of a magnetic nanopillar significantly affects the current-induced magnetization switching behavior by reducing the critical switching current density. Theoretical calculations reveal that increasing the spin relaxation in the capping layer enhances the spin-polarized current while suppresses the contribution of the spin accumulation to the magnetization switching. The results suggest that the spin-polarized current, rather than the spin accumulation, dominates the current-induced magnetization switching.

Magnetic anisotropy, exchange and damping in cobalt-based full-Heusler compounds: an experimental review

“…The critical current density for magnetization switching in the studied Co 2 Fe 0.5 Al 0.5 Si/MgO/Co 2 Fe 0.5 Al 0.5 Si nanopillars was 9.3×10 6 A/cm 2 . As anticipated, this current is lower than the critical current densities encountered in permalloy (∼ 1.1 × 10 7 A/cm 2 [194]) and Co/Cu/Co based devices (where current densities in the 2-12×10 7 A/cm 2 range were reported [195,196]). As such, we can anticipate the advantageous characteristics of Heusler compounds will be harnessed, and more investigations are expected as Heusler compounds are integrated into other STT-based devices, such as domain-wall nanowire shift register (also known as racetrack) memory [197] or STT magnetic random access memory (STT-MRAM) [13].…”

Spin-transfer switching in an epitaxial spin-valve nanopillar with a full-Heusler Co2FeAl0.5Si0.5 alloy

“…The intrinsic critical current density J c0 obtained was 9.3ϫ 10 6 A / cm 2 , which is much smaller than the typical values previously reported for Co/Cu/Co nanopillars, 9,10 and is comparable to those in Per-malloy ͑Py͒ based systems with a small magnetization ͑ϳ1.1ϫ 10 7 A / cm 2 ͒. In this letter, we report spin-transfer switching in a CFAS/Ag/CFAS CPP-GMR nanopillar.…”

Temperature dependence of intrinsic switching current of a Co nanomagnet

“…The fabrication process is described in a previous report. 17 Besides the measurement with the pulsed current, the differential resistance loop dV / dI ϳ I dc is also measured at each temperature by sweeping the dc current I dc at a step of 0.2 mA, as plotted in Fig. 1͑a͒.…”

“…Therefore, the intrinsic switching currents are also different. To check this effect, calculations of spin accumulation and spin polarization are carried out based on the one-dimensional spin diffusive equation with the transport parameters at 300/ 4.2 K: [17][18][19] Figure 4 shows the calculated spin accumulation ⌬ and spin polarization J S for the P state when the electrical current is 1 A/m 2 . It is clear that both the spin polarization and the spin accumulation are reduced at 4.2 K. Hence, the spin current is reduced, increasing the intrinsic switching current.…”