TY - JOUR
T1 - Spin transfer torque switching of Co/Pd multilayers and Gilbert damping of Co-based multilayers
AU - Kimura, Takumi
AU - Dong, Xiayin
AU - Adachi, Kanta
AU - Oshima, Daiki
AU - Kato, Takeshi
AU - Sonobe, Yoshiaki
AU - Okamoto, Satoshi
AU - Kikuchi, Nobuaki
AU - Kawato, Yoshiaki
AU - Kitakami, Osamu
AU - Iwata, Satoshi
N1 - Publisher Copyright:
© 2018 The Japan Society of Applied Physics.
PY - 2018/9
Y1 - 2018/9
N2 - The critical current density (Jc0) and thermal stability factor Δ for the spin transfer torque switching of [Pt/Co]6/Cu/[Co/Pd]3 nanopillars with various Co/Pd layer compositions were investigated. Moreover, the Gilbert damping constants α of Co/Pd and Co/Pt multilayers (MLs) with various layer compositions were also studied to understand the variations in the Jc0 and Δ of the nanopillars. The Jc0 and Δ of Co/Pd MLs were found to be almost independent of the pillar diameters, and the effective reversal size contributing to Δ was found to be much smaller than the physical pillar diameter. From the spin transfer torque (STT) switching of Co/Pd MLs with various layer compositions, Jc0 was found to gradually increase with increasing thickness ratio of Pd and Co layers, tPd/tCo, up to tPd/tCo = 2, and further increase in tPd/tCo resulted in the decrease in Jc0. On the other hand, Δ was roughly independent of the thickness ratio. The Gilbert damping constants α of Co/Pd and Co/Pt MLs increased with increasing thickness ratio of noble metal and Co layers, tNM/tCo. The large damping constant of the Co/Pt ML compared with that of the Co/Pd ML means that Co/Pt and Co/Pd MLs are appropriate for use as reference and memory layers, respectively. The increase in α with tPd/tCo is considered to be responsible for the increase in Jc0 up to tPd/tCo = 2.
AB - The critical current density (Jc0) and thermal stability factor Δ for the spin transfer torque switching of [Pt/Co]6/Cu/[Co/Pd]3 nanopillars with various Co/Pd layer compositions were investigated. Moreover, the Gilbert damping constants α of Co/Pd and Co/Pt multilayers (MLs) with various layer compositions were also studied to understand the variations in the Jc0 and Δ of the nanopillars. The Jc0 and Δ of Co/Pd MLs were found to be almost independent of the pillar diameters, and the effective reversal size contributing to Δ was found to be much smaller than the physical pillar diameter. From the spin transfer torque (STT) switching of Co/Pd MLs with various layer compositions, Jc0 was found to gradually increase with increasing thickness ratio of Pd and Co layers, tPd/tCo, up to tPd/tCo = 2, and further increase in tPd/tCo resulted in the decrease in Jc0. On the other hand, Δ was roughly independent of the thickness ratio. The Gilbert damping constants α of Co/Pd and Co/Pt MLs increased with increasing thickness ratio of noble metal and Co layers, tNM/tCo. The large damping constant of the Co/Pt ML compared with that of the Co/Pd ML means that Co/Pt and Co/Pd MLs are appropriate for use as reference and memory layers, respectively. The increase in α with tPd/tCo is considered to be responsible for the increase in Jc0 up to tPd/tCo = 2.
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U2 - 10.7567/JJAP.57.09TD01
DO - 10.7567/JJAP.57.09TD01
M3 - Article
AN - SCOPUS:85053340162
SN - 0021-4922
VL - 57
JO - Japanese journal of applied physics
JF - Japanese journal of applied physics
IS - 9
M1 - 09TD01
ER -