Frano, A.; Schierle, E.; Haverkort, M.W.; Lu, Y.; Wu, M.; Blanco-Canosa, S.; Nwankwo, U.; Boris, A.V.; Wochner, P.; Cristiani, G.; Habermeier, H.U.; Logvenov, G.; Hinkov, V.; Benckiser, E.; Weschke, E.; Keimer, B.: Orbital Control of Noncollinear Magnetic Order in Nickel Oxide Heterostructures. Physical Review Letters 111 (2013), p. 106804/1-5
10.1103/PhysRevLett.111.106804

Abstract:
We have used resonant x-ray diffraction to develop a detailed description of antiferromagnetic ordering in epitaxial superlattices based on two-unit-cell thick layers of the strongly correlated metal LaNiO3. We also report reference experiments on thin films of PrNiO3 and NdNiO3. The resulting data indicate a spiral state whose polarization plane can be controlled by adjusting the Ni d-orbital occupation via two independent mechanisms: epitaxial strain and spatial confinement of the valence electrons. The data are discussed in light of recent theoretical predictions.