Mark Filipkowski joined our department in the Fall of 1994, coming to us with a Bachelor's and Master's degree from the University of Pennsylvania, a Ph.D. from the University of Connecticut, and three years of Postdoctoral work at the Naval Research Laboratory. He specializes in condensed matter physics and materials research, with emphasis on the magnetic properties of thin films. His experimental methods include DC (SQUID) magnetometry and AC mutual inductance techniques, computerized megnetotransport detection, electron spin resonance, and ferromagnetic resonance spectroscopy. Upon arriving at the University of Arkansas, he had already authored or co-authored 17 refereed journal articles and two proceedings articles, and given two invited presentations and and nine contributed presentations. He describes his research as follows:
With the development of techniques for producing materials not found in nature, many new and exciting phenomena have become available for study in the field of condensed matter physics. The latter is that subdiscipline of physics devoted to the study of condensed systems, such as liquids and solids. The investigation of novel human-made materials has resulted in the discovery of "new physics" of interest to the general scientific community, and has the potential for the creation of new technologies.
A significant part of the study of condensed systems involves the examination of magnetic effects. These may range from the influence of the magnetic moment of the helium nucleus on the material phases of liquid helium, to improving the properties of permanent magnets. An example of an important class of new, human-made magnetic materials consists of layered structures, in which ultrathin layers of magnetic metals such as iron are sandwiched with nonmagnetic metals such as aluminum. "Ultrathin" refers to thicknesses of several angstroms, or only a few atoms.
New physics becomes possible in such systems due to the creation within the nonmagnetic metal of a magnetic polarization induced by the adjacent magnetic metal. The properties of the nonmagnetic metal are thus perturbed in a way heretofore impossible. Forming a complete picture of how this polarization comes about, and the nature and extent of its influence on the properties of the nonmagnetic metal, is a very active experimental and theoretical research area.
The goal of my laboratory is to understand the fundamental physical principles governing the behavior of layered and other novel magnetic systems. In this way we will contribute to the growth of knowledge in condensed matter physics, and help lay the groundwork for future technological advances.
We will explore the physics of novel magnetic materials by using such sophisticated experimental techniques as SQUID- (Superconducting Quantum Interference Device) based magnetometry, nuclear magnetic resonance, and spin-polarized transport. In addition, an extremely profitable set of interdisciplinary experiments becomes possible at the University of Arkansas through combined efforts with optical laboratories within the Department of Physics. These experiments will investigate the time dependence of magnetic phenomena using fast optical techniques, and the coupling of magnetic layers through nonmagnetic layers using the method of Brioullin light scattering.*