Volume 96, Number 3, November 2011
|Number of page(s)||6|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||17 October 2011|
Bandwidth-driven nature of the pressure-induced metal state of LaMnO3
Institut Néel, CNRS et Université Joseph Fourier - BP 166, F-38042 Grenoble Cedex 9, France, EU
2 Advanced Photon Source, Argonne National Laboratory - Argonne, IL 60439, USA
3 Laboratório Nacional de Luz Síncrotron - P.O. Box 6192, 13084-971, Campinas, São Paulo, Brazil
4 Synchrotron SOLEIL - L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France, EU
5 Centro Atómico Bariloche, CNEA and Universidad Nacional de Cuyo - 8400 S.C. de Bariloche, Argentina
Accepted: 8 August 2011
Using X-ray absorption spectroscopy (XAS), we studied the local structure in LaMnO3 under applied pressure across and well above the insulator-to-metal (IM) transition. A hysteretic behavior points to the coexistence of two phases within a large pressure range (7 to 25 GPa). The ambient phase with highly Jahn-Teller (JT) distorted MnO6 octahedra is progressively substituted by a new phase with less-distorted JT MnO6 units. The electronic delocalization leading to the IM transition is finger-printed from the pre-edge XAS structure around 30 GPa. We observed that the phase transition takes place without any significant reduction of the JT distortion. This entails band overlap as the driving mechanism of the IM transition.
PACS: 61.50.Ks – Crystallographic aspects of phase transformations; pressure effects / 71.70.Ej – Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect / 71.30.+h – Metal-insulator transitions and other electronic transitions
© EPLA, 2011
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