Tuning interlayer exchange coupling of co-doped TiO2/VO2 multilayers via metal-insulator transition.

Reversibly switching interlayer exchange coupling (IEC) of magnetic semiconductor multilayers between ferromagnetic (FM) and antiferromagnetic (AFM) modes is a difficult but key issue for fabricating semiconductor giant magnetoresistance devices. Here, we show that such tunable IEC is achievable around room temperature in Co-doped TiO2/VO2 diluted magnetic semiconductor multilayers. On the basis of first-principles calculations of electronic structure and fermiology, it is clarified that, associated with the metal-insulator transition (MIT) of nanosized VO2 spacers, exotic short-range magnetic orders are developed in the multilayers so that the IEC can be tuned reversibly from FM mode to AFM mode by varying temperature crossing the MIT (∼340  K).