Tunable charge and spin order in PrNiO3 thin films and superlattices
M. Hepting, M. Minola, A. Frano, G. Cristiani, G. Logvenov, M. Wu, M. Bluschke, H.-U. Habermeier, E. Benckiser, M. Le Tacon, and B. Keimer
We have used Raman scattering to probe lattice vibrations and charge ordering (CO) in PrNiO3 thin films, and in superlattices (SLs) of PrNiO3 and PrAlO3. In films and SLs under tensile strain, phonon modes characteristic of CO are revealed in the insulating phase. These anomalous phonons do not appear in compressively strained films and SLs, which remain metallic at all temperatures. The SLs on compressive strain, however, exhibit antiferromagnetic order, confirming theoretical predictions of a spin density wave phase driven by spatial confinement of the conduction electrons.