Enhancing s, p–d exchange interactions at room temperature by carrier doping in single crystalline Co0.4Zn0.6O epitaxial films

Magnetic doping of semiconductors has been actively pursued because of their potential applications in the spintronic devices. Central to these efforts is a drive to control the mutual interactions between their magnetic properties (supported by d electrons of the magnetic ions) and their semiconductor properties (supported by s and/or p electrons) at room temperature (RT). Despite the long, intensive efforts, the experimental evidence of thermally robust s, p–d coupling in a semiconductor remains scarce and controversial. Here, we report the enhancement of RT ferromagnetic s, p–d exchange interaction by means of carrier doping in single crystalline Co0.4Zn0.6O epitaxial films with a high Co concentration. Magneto-transport measurements reveal that spin-polarized conducting carriers are produced at RT and are increased with the carrier density through Ga3+ doping, owing to the s, p–d coupling between Ga (4s), O (2p), and Co (3d) orbitals. With the ability to individually control carrier density and magnet...