Spin transfer switching of closely arranged multiple pillars with current-perpendicular-to-plane spin valves

Abstract

Spin transfer switching (STS) characteristics of two closely arranged spin valve (SV) pillars sharing a pair of top and bottom electrodes were investigated. Each pillar had a 300×100nm2 rectangular shape, which was fabricated by electron beam lithography. The separation between the pillars was 300nm or 1μm. The STS curves clearly show the two-step switching of the free layer for the device with a separation of 300nm. The first switching occurred at a switching current density of a single SV pillar or below. The second switching occurred at a switching current density approximately 1.2 times the first one. Furthermore, the STS characteristics of the paired free layers were estimated by a micromagnetic simulation using the Landau–Lifshitz–Gilbert–Slonczewski equation, which showed similar switching behavior to the experimental result of the free layers switched first.