Storage as well as sensing devices of modern micro- nanoelectronics are based on integrated semiconductor technology. Most of the resulting devices have disadvantage such as being volatile or non flexible after production. In, e.g., data storage magnetic hard disk drives store data permanently, but are much slower than their RAM counterparts. Here, the Magnetic Random Access Memory (MRAM) is a promising perspective to combine the benefits of fast access/writing speeds and non-volatility. This concept, spin-dependent transistor devices or read heads with a current perpendicular to the plane can be based on the magnetic tunnel junction.
Within this general field, our research is targeted towards further steps, investigating field programmable logic gate arrays (FPGA) based on magnetoelectronic devices. Circuits could 'rewire' themselves to solve particular problems much faster than general central processing units (CPU) and make specialized chips on graphic or sound cards obsolete.
To get fast writing times in these magnetic devices, the magnetization dynamics are very important. Therefore we additionally study the dynamics of magnetic nanostructures and magnetic tunnel junctions in terms of spin wave excitation and X-ray circular dicroism in collaboration with research groups in Münster, Braunschweig, Kaiserslautern, Stuttgart and Berkeley. The so called spin torque switching is investigated as well to further lower the size and enhance the performance of integrated devices.
Finally, scanning microscope techniques are used to investigate new fields of research, such as molecular magnets on top of magnetic tunnel junctions.
For my research profile please visit research id:
Please send emails to Günter Reiss (reiss@physik.uni-bielefeld.de).
G. Reiss, J. Schmalhorst, A. Thomas, A. Hütten, S. Yuasa: 'Magnetic Tunnel Junctions', Springer Tracts in Modern Physics 227 (2008) 291 - 333
B. Van Waeyenberge, A. Puzic, H. Stoll, K.W. Chou, T. Tyliszczak, R. Hertel, M. Fähnle, H. Brückl, K. Rott, G. Reiss, I. Neudecker, D. Weiss, C. H. Back, G. Schütz: 'Magnetic vortex core reversal by excitation with short bursts of an alternating field', Nature 444 (2006) 461
V. E. Demidov, S. O. Demokritov, K. Rott, P. Krzysteczko, G. Reiss: 'Mode interference and periodic self-focusing of spin waves in permalloy microstripes', Phys. Rev. B, in press
