Spectral Weight Redistribution in $({\mathrm{LaNiO}}_3{)}_n/({\mathrm{LaMnO}}_3{)}_2$ Superlattices from Optical Spectroscopy

Journal Article · Wed Apr 01 00:00:00 EDT 2015 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.114.156801· OSTI ID:1356977

Di Pietro, P.; Hoffman, J.; Bhattacharya, A.; Lupi, S.; Perucchi, A.

We have studied the optical properties of four (LaNiO3)(n)/(LaMnO3)(2) superlattices (SL) (n = 2, 3, 4, 5) on SrTiO3 substrates. We have measured the reflectivity at temperatures from 20 to 400 K, and extracted the optical conductivity through a fitting procedure based on a Kramers-Kronig consistent Lorentz-Drude model. With increasing LaNiO3 thickness, the SLs undergo an insulator-to-metal transition (IMT) that is accompanied by the transfer of spectral weight from high to low frequency. The presence of a broad midinfrared band, however, shows that the optical conductivity of the (LaNiO3)(n)/(LaMnO3)(2) SLs is not a linear combination of the LaMnO3 and LaNiO3 conductivities. Our observations suggest that interfacial charge transfer leads to an IMT due to a change in valence at the Mn and Ni sites.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1356977
• Journal Information: Physical Review Letters, Vol. 114, Issue 15; ISSN 0031-9007
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English