Regensburg 1998 – wissenschaftliches Programm
SYE 1.1: Hauptvortrag
Donnerstag, 26. März 1998, 09:30–10:00, H 16
Latest developments of the Spin Valve Transistor — •J.C. Lodder, D.J. Monsma, and R. Vlutters — Information Storage Technology Group, MESA Research Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, Niederlande
Magnetic recording density of 5 Gbit/in2 has been demonstrated by using GMR-read sensor in the recording head. In this case the so-called current in plane (CIP) measuring principle was used. However this suffers from several drawbacks and is diminished by shunting and channelling. Measuring with the current perpendicular to the planes (CPP) solves most of the problems, mainly because the electrons cross all magnetic layers but the difficulty is that the resistance off the very thin multilayers is too small to be measured by ordinary technologies. Since 1991 various configurations have been proposed. In 1995 a new CPP-MR sensor design was introduced by our group based on the principle of a Metal Base Transistor. In the so called Spin Valve Transistor (SVT) a GMR multilayer (e.g. Co/Cu) serves as a base region of an n-Si metal-base structure. A 215 collector current is found in 40 kA/m at 77K with typical characteristics of a spin valve effect. The device is biased to inject hot electrons from one Si layer through the multilayer, the latter magnetic configuration determining what proportion of this current eventually passes the second Schottky barrier. The latest developments will be reported about the bonding technology during sputtering and lithographic processes to reduce the dimensions of the device to make operation at RT possible. This technology and the realisation of an SVT also establishes the feasibility of combining Si technology and spin electronics. In more general the combination of nano magnetism and nano electronics gives the possibility to realise new devices and memory functions.