Seminar Details

Current-Perpenduclar-to-Plane (CPP) Giant Magnetoresistance (GMR) Studies at MSU

Jack Bass, MSU
Thursday, February 9, 4:10 PM - Physics and Astronomy Colloquium
Biomedical & Physical Sciences Bldg., Rm. 1415

Jack Bass (with William P. Pratt Jr. and P.A. Schroeder) In 1988, A.Fert and P. Grunberg independently discovered Giant Magnetoresistance (GMR) in Current-in-Plane (CIP) measurements on Ferromagnetic/Non-magnetic (F/N) multilayers of antiferromagnetically coupled Fe/Cr. In 2006 they shared the Noble Prize for their discovery, for the wide-ranging physics and technologies (including both sensors and computer read-heads) to which it gave birth. Iíll argue that the alternative Current-Perpendicular-to-Plane (CPP) geometry, pioneered at MSU in 1991, is not only often larger than the CIP-MR, but obeys simpler equations, giving more direct access to the detailed physics underlying GMR. Over the past two decades, we have used unique experimental capabilities to determine, for a wide variety of both F/N and N1/N2 multilayers, the parameters that characterize both the individual layers and their interfaces. Only a few of these parameters (all within layers) were known from prior measurements of other kinds. We used those known parameters to help test and validate the models that we use to analyze our data. For the rest of the parameters (especially all of those for interfaces), essentially nothing was known when we began. Iíll describe how we determine such parameters and what we find. Of special interest are cases where we can now compare our derived parameters with calculations involving no adjustability.