We present switching field distributions of spin-transfer assistedmagnetization reversal in perpendicularly magnetized Co/Ni multilayerspin-valve nanopillars at room temperature. Switching field measurements of theCo/Ni free layer of spin-valve nanopillars with a 50 nm x 300 nm ellipse crosssection were conducted as a function of current. The validity of a model thatassumes a spin-current dependent effective barrier for thermally activatedreversal is tested by measuring switching field distributions under applieddirect currents. We show that the switching field distributions deviatesignificantly from the double exponential shape predicted by the effectivebarrier model, beginning at applied currents as low as half of the zero fieldcritical current. Barrier heights extracted from switching field distributionsfor currents below this threshold are a monotonic function of the current.However, the thermally-induced switching model breaks down for currentsexceeding the critical threshold.
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机译：我们提出了在室温下垂直磁化的Co / Ni多层自旋阀纳米柱中自旋转移辅助磁化反转的开关场分布。根据电流对具有50 nm x 300 nm椭圆形横截面的自旋阀纳米柱的Co / Ni自由层进行开关场测量。通过测量施加的直流电下的开关场分布来测试假设模型的有效性，该模型假设自旋电流依赖于热激活逆转的有效势垒。我们表明，开关场分布与有效势垒模型预测的双指数形状明显不同，从施加的电流低至零场临界电流的一半开始。对于低于此阈值的电流，从开关场分布中提取的势垒高度是电流的单调函数，但是，对于超过临界阈值的电流，热感应开关模型会崩溃。
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