Materials for Magnetic Devices { Magneto-Electronics and Recording Chairs

Withdrawn. EXCHANGE COUPLING AND SPIN-FLIP TRANSITION OF CoFe O / -Fe O BILAYERED FILMS. Tatsuo Fujii, Takuya Yano, Makoto Nakanishi and Jun Takada, Dept of Applied Chemistry, Okayama Univ, Okayama, JAPAN. (102)-oriented -Fe O epitaxial lms deposited on -Al O (102) are known to have an unique spinip transition at about 400 K [1]. The spin axis lying within the (102) plane above 400 K changes almost normal the plane at room temperature. We will report the magnetic properties of CoFe O / -Fe O bilayered lms. The spinip transition of -Fe O could in uence the magnetic properties of CoFe O , and vice versa. CoFe O / -Fe O (ferrimagnetic / antiferromagnetic) bilayered lms on -Al O (102) were prepared by helicon plasma sputtering method. The CoFe O layer grown on -Fe O (102) had an (100)-preferred orientation. Magnetization and Mossbauer measurements of bilayered lms suggested that the CoFe O layer had an in-plane magnetic anisotropy while the -Fe O (102) had the spins aligned perpendicular to the lm plane. The bilayered lms did not show the spinip transition. The ferrimagnetic spins of the CoFe O layer were coupled perpendicularly to the antiferromagnetic spins of the -Fe O layer, due to the exchange coupling between CoFe O and -Fe O . The large in-plane anisotropy of the CoFe O layer could suppress the spinip transition of the -Fe O layer. [1] T.Fujii, M. Takano, R. Katano, Y. Isozumi and Y. Bando, J. Magn. Magn. Mat, 135(1994) 231. SESSION T2: MICROMAGNETICS TO NANOMAGNETICS { THE NEXT STEP Chairs: Edward S. Murdock and Olle Heinonen Tuesday Afternoon, April 17, 2001 Golden Gate C3 (Marriott) MAGNETIC AND MAGNETORESISTIVE PROPERTIES OF NANOPATTERNED ELEMENTS. C.A. Ross, Y. Hao,. F. Castano, S. Haratani, Dept. of MS&E, Massachusetts Institute of Technology, Cambridge, MA; Henry I. Smith, B. Vogeli, M. Walsh, Dept. Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA. Many magnetoelectronic devices, such as read heads and magnetic random access memories, are based on small magnetoresistive elements whose resistance is a function of their magnetization state. These elements usually consist of a multilayer stack which includes magnetic lms, non-magnetic spacers, and pinning layers such as antiferromagnets. As the elements become smaller, magnetostatic coupling between the magnetic layers dominates the behavior, leading to antiparallel alignment of the magnetic layers and raising their switching elds. In this work, we have used nanolithography techniques to pattern magnetoresistive elements with diameters of 50 nm and lengths of 100 nm and above, to examine how the magnetic and magnetoresistive behavior scales with element size. Films such as Co/Cu/NiFe pseudo-spin valves are sputtered then patterned into arrays of elements using interference lithography combined with ion milling. The magnetic hysteresis of the arrays is measured using magnetometry and magnetic force microscopy, and the magnetoresistance is measured by connecting the arrays with conductor lines in a self-aligned lithography process. As an example, in an unpatterned Co 4 nm/Cu 3 nm/NiFe 6 nm lm the magnetic