Room-temperature magnetocurrent in antiferromagnetically coupled Fe/Si/Fe

Epitaxial Si-based ferromagnet/semiconductor structures demonstrate strong antiferromagnetic coupling (AFC) as well as resonant-type tunneling magnetoresistance, which vanishes at temperatures above T$\sim $50K [1]. Magnetoresistance effects in Fe/Si/Fe close to room temperature (RT) were not established yet. By using the ballistic electron magnetomicroscopy (BEMM) techniques, with its nanometer-scaled locality [2] we observed for the first time a spin-dependent ballistic magnetotransport in AFC structures. We found that the hot-electron collector current with energies above the Fe/GaAsP Schottky barrier reflects magnetization alignment and changes from I$_{cAP}\sim $50fA for antiparallel alignment to I$_{cP}\sim $150fA for the parallel one. Thus, the magnetocurrent [(I$_{cP}$-I$_{cAP})$/ I$_{cAP}$]*100{\%} is near 200 {\%} at RT. The measured BEMM hysteresis loops match nicely with the magnetic MOKE data.\\[0pt] [1]. R.R. Gareev, M.Weides, R. Schreiber, U. Poppe, Appl. Phys. Letts \textbf{88}, 172105 (2006); [2]. E. Heindl, J. Vancea, C.H. Back, Phys. Rev.\textbf{B75}, 073307 (2007).