Antiferromagnetic coupling across silicon regulated by tunneling currents

We report on the enhancement of antiferromagnetic coupling in epitaxial Fe/Si/Fe structures by voltage-driven spin-polarized tunneling currents. Using the ballistic electron magnetic microscopy we established that the hot-electron collector current reflects magnetization alignment and the magnetocurrent exceeds 200% at room temperature. The saturation magnetic field for collector current corresponding to parallel alignment of magnetizations rises up with the tunneling current, thus demonstrating stabilization of the antiparallel alignment and increasing antiferromagnetic coupling. We connect the enhancement of antiferromagnetic coupling with local dynamic spin torques mediated by tunneling electrons