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Another Advance on the Road to Spintronics Print
Monday, 15 October 2012 16:20

Spintronic technology, in which data is processed on the basis of electron “spin” rather than charge, promises to revolutionize the computing industry with smaller, faster and more energy efficient data storage and processing. Dilute magnetic semiconductors –normal semiconductors to which a small amount of magnetic atoms is added to make them ferromagnetic—are drawing a lot of attention for spintronic applications. Understanding the source of ferromagnetism in dilute magnetic semiconductors has impeded their further development and use in spintronics. Now, a multi-institutional collaboration of researchers led by Berkeley Lab scientists have used a new technique called Hard x-ray Angle-Resolved PhotoEmission Spectroscopy (HARPES) at ALS Beamline 9.3.1 to investigate the bulk electronic structure one dilute magnetic semiconductor. Their findings show that the material’s ferromagnetism arises from both of the two different mechanisms that have been proposed to explain it.

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With the HARPES technique, a beam of hard x-rays flashed on a sample causes photoelectrons from within the bulk to be emitted. Measuring the kinetic energy of these photoelectrons and the angles at which they are ejected reveals much about the sample’s electronic structure. Here the Mn atoms in GaMnAs are shown to be aligned ferromagnetically, with all their atomic magnets pointing the same way. (Image from Alex Gray)