Metal/Metal Interface Resistances W. Pratt, Jr. & J. Bass, Michigan State University, DMR-0501013

1. perfect interface intermixed interface M1 M2 M1 M2 Fe/Cr[110] Co/Cu[111] Pd/Pt [111] Ag/Au [111] Metal/Metal Interface Resistances W. Pratt, Jr. & J. Bass, Michigan State University, DMR-0501013 Scattering of electrons from interfaces plays a crucial, sometimes even dominant, role in the electrical resistances of multilayers composed of alternating layers of metals M1 and M2. To design new devices containing such multilayers requires knowing the strength of interfacial scattering and understanding its origins. Two fundamental questions are: Is scattering at an M1/M2 interface determined primarily by the band structures of M1 and M2?; How sensitive is the interface specific resistance AR (area A times resistance R) to whether the interface is ‘perfect’ or intermixed? For metals M1 and M2 with the same crystal structure and the same lattice parameter to within 1%, AR can be calculated with no adjustable parameters. For all four such metal pairs so-far studied, the calculations agree to within mutual uncertainties (see figure) with our values of AR measured on sputtered multilayers with current flowing perpendicular to the interfaces. The very different values of AR are due to different mismatches of band structures, and the calculations are not sensitive to interfacial intermixing.

2. Metal/Metal Interface Resistances W. Pratt, Jr. & J. Bass, Michigan State University,DMR-0501013 Technological Significance: Our determinations of bulk and interfacial parameters of magnetic and non-magnetic multilayers in the current-perpendicular-to-plane (CPP) geometry provide a major part of the information used to estimate the viability of devices using this geometry and to design such devices—including a future generation of read heads in computer hard drives. We have also made important contributions to the subject of current-induced magnetization switching (CIMS), another phenomenon with potential device applicability in magnetic random-access memories and microwave sources. Education: We supervise a postdoctoral student (female), two Ph.D. students, undergrads, and visitors. In 2006 the latter two included an REU undergraduate (female) and a senior Korean visitor. Outreach and Service: This year J. Bass is serving as Past-Chair of GMAG and also served on the organizing committee for the MMM/Intermag Meeting in Jan. 2007. W. Pratt is serving on the Executive Board of the Michigan Chapter of the American Vacuum Society. As a service to the broader physics community, we are writing an invited review article on Spin-Diffusion Lengths in Metals and Alloys and Spin Flipping at Metallic Interfaces, topics to which we have made significant contributions.