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

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 mu(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 mus 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. (C) 2004 American Institute of Physics.