Low Energy Electrodynamics in Solids 2012

Optical Properties of (SrMnO3)n/(LaMnO3)2n Superlattices: An Insulator-to-Metal Transition Observed in the Absence of Disorder

23 Jul 2012, 20:00

2h

Fountain Court (Embassy Suites Napa Valley)

Board: 13

Poster Metal-Insulator Systems Poster Session 1

Speaker

Andrea Perucchi (ELETTRA - Sincrotrone Trieste)

Description

A. Perucchi1, L. Baldassarre1, A. Nucara2, P. Calvani2, C. Adamo3, D.G. Schlom3, P. Orgiani4, L. Maritato4, S. Lupi5 1) Sincrotrone Trieste, Area Science Park, I-34012 Trieste, Italy 2) CNR-SPIN and Dipartimento di Fisica, Università Sapienza, P.le A. Moro 2, I-00185 Rome, Italy 3) Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501, USA 4) CNR-SPIN and Dipartimento di Matematica ed Informatica, Università di Salerno, Baronissi, I-84081 Salerno, Italy 5) CNR-IOM and Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, I-00185 Rome, Italy We measure the optical conductivity, σ1(ω), of (SrMnO3)n/(LaMnO3)2n superlattices (SL) for n=1, 3, 5, and 8 and 10 < T < 400 K. Data show a T-dependent insulator to metal transition (IMT) for n=3, driven by the softening of a polaronic mid-infrared band. At n=5 that softening is incomplete, while at the largest-period n=8 compound the MIR band is independent of T and the SL remains insulating. One can thus first observe the IMT in a Manganite system in the absence of the disorder due to chemical doping. Unsuccessful reconstruction of the SL optical properties from those of the original bulk materials suggests that (SrMnO3)n/ (LaMnO3)2n heterostructures give rise to a novel electronic state.