Antiferromagnetic Spin Reorientation Transition induced by the coupling at NiO/CoO interface

Manipulating the antiferromagnetic (AFM) spin orientation is important for spitronic researches. But AFM spin-reorientation transition (SRT) can be realized only through limited mechanisms. In this contribution, we realized an in-plane to out-of-plane AFM SRT in NiO/CoO/MgO(001) system through a new mechanism, i.e., the exchange coupling between AFM spins. NiO and CoO spin orientations were determined by X-ray magnetic linear dichroism (XMLD) measurements. The CoO spin was fixed in-plane below Néel temperature (T$_{\mathrm{N}})$, while the NiO spin undergoes an in-plane to out-of-plane SRT above a critical NiO thickness. The SRT is attributed to the competition between NiO out-of-plane anisotropy from expansive strain and in-plane anisotropy from interfacial coupling with CoO spin. The SRT was influenced by CoO AFM ordering modulated by temperature, CoO thickness and interfacial coupling strength tuned by the thickness of MgO layer inserted between NiO and CoO. Besides, temperature-dependent XMLD measurement indicated a rise of CoO T$_{\mathrm{N}}$ by 80K with the proximity effect from NiO. Our experimental results can be further understood by Monte Carlo simulations.