June 19, 2014
- Recent research in collaboration with UMN Prof. Paul Crowell of the School of Physics and Astronomy, Dr. Valeria Lauter of Oak Ridge National Lab, CEMS post-doc Dr. Liam O'Brien and CEMS Prof. Chris Leighton have advanced a solution to a longstanding puzzle in nanoscale magnetic devices. The work, "Kondo physics in non-local metallic spin transport devices," was recently published in the journal Nature Communications. The devices in question are composed of thin film magnetic metals that inject spin-polarized currents into nanowires of non-magnetic metals and are considered leading candidates for next-generation sensors in hard disk drives. The efficiency of such devices unexpectedly decreases on cooling, an effect that has perplexed researchers for years. In this work, the CEMS/UMN/Oak Ridge research team discovered that this behavior is not a property of the magnetic or non-magnetic metal alone, but rather a property of the interface between the pair of metals. The effect was shown to be due to magnetic atoms diffusing into the non-magnetic nanowire in part-per-million quantities, leading to a phenomenon known as the Kondo effect. Significantly, appropriately designed interfaces were shown to almost completely eliminate the effect, restoring the efficiency of spin injection. The figure shows an electron microscopy image of a non-local metallic spin transport device used in the work.
Related Link: http://www.nature.com/ncomms/2014/140529/ncomms4927/full/ncomms4927.html