Keywords:ferromagnetic semiconductor, giant magnetoresistance, spintronics
We demonstrate the giant magnetoresistance (GMR) effect in spin valve structures using high-TC (Ga,Fe)Sb. The samples examined here consist of (Ga0.75,Fe0.25)Sb (40 nm, TC > 320 K)/ InAs (thickness t = 0, 3, 6, 9 nm)/ (Ga0.8,Fe0.2)Sb (40 nm, TC > 320 K) grown by low temperature molecular beam epitaxy (LT-MBE) and are measured at 3.7 K with a magnetic field H applied perpendicular to the film plane. Clear GMR of ~2% with open minor loop is observed in t = 3 nm sample, whose peaks (~ ±0.1 T) are consistent with the coercive forces of the magnetizations of the (Ga,Fe)Sb layers obtained with superconducting quantum interference device (SQUID) magnetometry. We found that the GMR ratio increases (from 0.03 to 1.28%) with decreasing t (from 9 to 3 nm), which is caused by the enhancement of scattering at the InAs/(Ga,Fe)Sb interfaces. This first demonstration of the spin-valve (GMR) effect in Fe-doped FMS heterostructures paves the way for device applications of these promising high-TC FMSs.