Bandwidth-driven nature of the pressure-induced metal state of LaMnO3

A.Y. RAMOS; N.M. SOUZA NETO; H.C.N. TOLENTINO; O. BUNAU; Y. YOLY; S. GRENIER; J.P. ITIÉ; A.M. FRANK; P. LAGARDE; A. CANEIRO

EUROPHYSICS LETTERS

EPL ASSOCIATION

Lugar: Bologna; Año: 2011 vol. 96 p. 36002 - 36008

0295-5075

Using X-ray absorption spectroscopy (XAS), we studied the local structure in LaMnO3under applied pressure across and well above the insulator-to-metal (IM) transition. A hystereticbehavior points to the coexistence of two phases within a large pressure range (7 to 25GPa). Theambient phase with highly Jahn-Teller (JT) distorted MnO6 octahedra is progressively substitutedby a new phase with less-distorted JT MnO6 units. The electronic delocalization leading to the IMtransition is finger-printed from the pre-edge XAS structure around 30GPa. We observed that thephase transition takes place without any significant reduction of the JT distortion. This entailsband overlap as the driving mechanism of the IM transition.