Abstract
We present a study of the interfacial interaction between a ferromagnetic metallic manganite in proximity to a charge-ordered manganite in a bilayer structure. Different thicknesses (2–45 nm) of ferromagnetic metallic NdSrMnO (NSMO-1/3) were grown by pulsed laser ablation on charge-ordered NdCaMnO (NCMO-1/2) with a fixed thickness of 175 nm on SrTiO (001) substrates. Electrical transport and magnetization measurements in large magnetic fields show that the metal-insulator transition temperature decreases with the NSMO-1/3 thickness down to a critical value of 4–5 nm below which NSMO-1/3 remains insulating at low temperature. The critical thickness corresponds also to the largest magnetoresistance response with the conducting phase recovered easily under the application of a magnetic field as low as 1.5 T. The insulating phase observed for the ultrathin NSMO-1/3 film is attributed to the compressive strain and the magnetic interaction in the vicinity of the charge-ordered NCMO-1/2. Magnetic measurements also show that a significant portion of the NCMO-1/2 layer magnetizes at lower field. This is a clear example of a forced phase percolation by proximity effect.
- Received 11 November 2010
DOI:https://doi.org/10.1103/PhysRevB.84.104434
©2011 American Physical Society