Surface electronic and magnetic properties of La2/3Sr1/3MnO3 thin films with extended metallicity above the Curie temperature

R. Bertacco, A. Tagliaferri, M. Riva, L. Signorini, M. Cantoni, A. Cattoni, F. Ciccacci, B. A. Davidson, F. Maccherozzi, I. Vobornik, and G. Panaccione
Phys. Rev. B 78, 035448 – Published 31 July 2008

Abstract

The surface electronic and magnetic properties of epitaxial La2/3Sr1/3MnO3/SrTiO3(001) films with extended bulk metallicity above the Curie temperature have been investigated. By angle-resolved photoemission we show that the surface electronic structure presents the eg dispersing band, responsible for the half-metallicity, crossing the Fermi level and leading to a sharp Fermi edge. Quasiparticle excitations, reflecting the coherent polaronic ferromagnetic and metallic ground state, are clearly visible at the Fermi level and 16 K, while they disappear at room temperature, where a Fermi edge is still clearly visible. X-ray magnetic circular dichroism shows a robust subsurface magnetization up to TC, while spin-polarization Mott spectroscopy indicates a rapid suppression of the surface magnetization which disappears around room temperature. These results clearly demonstrate that a robust surface metallic electronic structure does not necessarily ensure the concomitant stabilization of long-range magnetic order.

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  • Received 18 June 2007

DOI:https://doi.org/10.1103/PhysRevB.78.035448

©2008 American Physical Society

Authors & Affiliations

R. Bertacco, A. Tagliaferri, M. Riva, L. Signorini, M. Cantoni, A. Cattoni, and F. Ciccacci

  • L-NESS, Dipartimento di Fisica, Politecnico di Milano, via Anzani 42, 22100 Como, Italy

B. A. Davidson, F. Maccherozzi, I. Vobornik, and G. Panaccione

  • CNR-INFM TASC National Laboratory, S.S. 14 Km 163.5 in AREA Science Park, Basovizza, 34012 Trieste, Italy

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Issue

Vol. 78, Iss. 3 — 15 July 2008

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