Observation of thermal switching of a single ferromagnetic particle
Observation of thermal switching of a single ferromagnetic particle
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单个铁磁颗粒热开关的观察
DOI：
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发表时间：
1993
期刊：
影响因子：
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通讯作者：
S. Schultz
中科院分区：
文献类型：
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作者：
M. Lederman;G. Gibson;S. Schultz
磁力显微镜（Magnetic Force Microscope，MFM）已经被证明能够探测到磁矩低至10−13 emu的亚微米坡莫合金粒子所发出的磁场。我们已经使用这种配备有原位电磁铁的MFM来研究开关场Hs（θ）的角度依赖性，以及单畴坡莫合金粒子的热开关概率作为施加磁场H的持续时间的函数。Hs（θ）的角度依赖性与相干旋转的预期显著不同。对于接近Hs的外加磁场，不切换的概率的时间依赖性不能用简单的指数拟合。这些数据表明，类似高度的多能垒参与了导致反转的热激活过程。
A magnetic force microscope (MFM) has been shown to be able to detect fields emanating from submicrometer permalloy particles with magnetic moments as low as 10−13 emu. We have used this MFM equiped with an in situ electromagnet to study the angular dependence of the switching field Hs(θ), and the probability of thermal switching of a single‐domain permalloy particle as a function of the time duration of an applied magnetic field H. The angular dependence of Hs(θ) is significantly different from that expected for coherent rotation. For applied magnetic fields close to Hs, the time dependence of the probability for not switching cannot be fit with a simple exponential. These data indicate that multiple‐energy barriers of similar height are involved in the thermally activated process responsible for the reversal.