EPITAXIAL-GROWTH AND GIANT MAGNETORESISTANCE OF CO/CU(111) SUPERLATTICES ON CR BUFFER LAYERS

The Co/Cu superlattices have been prepared by molecular-beam epitaxy on Si(001) substrates with a Cr buffer layer. X-ray-diffraction experiments showed that highly (111)-oriented superlattices were obtained. The magnetoresistance was investigated as a function of Cu spacer thickness t(Cu) from 20 to 45 Angstrom. The giant magnetoresistance (GMR) is oscillatory and the period of oscillation is about 8-9 Angstrom. The maximum GMR was found as high as 10% with 300 Oe low field at room temperature. In addition, the resistance versus field curves were found to be clearly hysteretic, and the fields corresponding to the maximum resistence R(max) are oscillatory with Cu layer increasing, as long as the saturated field has oscillatory changes with t(Cu).