Low-current spin-transfer switching and its thermal durability in a low-saturation-magnetization nanomagnet

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Abstract
A spin-transfer magnetization switching technique is a promising candidate as a writing mechanism for a high-density magnetic random access memory because of its scalability. The required switching current I c , however, is still too large for this technique to be applied to MRAM using tunneling magnetoresistive devices. Here, it is demonstrated that reducing the saturation magnetization M s of magnet cells is an effective way to decrease I c . Use of a CoFeB film with μ 0 M s of 0.75 T as a magnet cell reduced I c measured with a continuous current by an order of magnitude. We changed the duration of a writing current pulse from 1 μ s to 5 s to investigate thermal effects on the switching process, and predicted that CoFeB magnet cells with low I c can be compatible with the thermal durability required for MRAM applications.