Spin torque effects in magnetic tunnel junctions – Olle Heinonen

Date: Thu. September 9th, 2010, 4:15 pm-5:15 pm
Location: Rockefeller 301

The prediction by Slonczewski and Berger that currents in magnetic heterostructures can exert a torque on the magnetization in the structures has lead to intense research over the past decade. This is both because of a new area of fundamental physics made possible by coupling DC currents and spin dynamics, as well as technological applications, such as magnetic random access memories and nano-scale high-frequency oscillators, in spintronics. Magnetic tunnel junctions (MTJs) consist of two magnetic layers separated by an insulator. In such structures, spin torque can induce a range of magnetization dynamics from coherent oscillations to switching and chaotic motion.

In this presentation, I will go through some of the fundamentals of spin torque as well as some of its applications in magnetic tunnel junctions. In particular, I will talk about induced magnetization dynamics and switching, and how the spin torque can be studied using relatively simple noise frequency measurements. This latter part is an illustration of how noise is not just stuff we want to get rid of, but actually contains information!