Persistence of Jahn-Teller Distortion up to the Insulator to Metal Transition in LaMnO$_{3}$

High pressure, low temperature Raman measurements performed on LaMnO$_{3}$ up to 34~GPa provide the first evidence for the persistence of the Jahn-Teller distortion over the entire stability range of the insulating phase. This result resolves the ongoing debate about the nature of the pressure driveninsulator to metal transition (IMT), demonstrating that LaMnO$_{3}$ is not a classical Mott insulator. The formation of domains of distorted and regular octahedra, observed from 3 to 34~GPa, suggests that LaMnO$_{3}$ becomes metallic when the fraction of undistorted octahedra domains increases beyond a critical threshold. In this scenario, it is interesting to consider whether or not the CMR effect may be induced in LaMnO$_{3}$ by applying pressure. Preliminary results obtained performing high pressure resistivity measurements in a magnetic field will be reported. \\[4pt] [1] I. Loa, et al., \textit{Phys. Rev. Lett.} 87, 125501 (2001). \\[0pt] [2] A.Y. Ramos et al., \textit{Phys. Rev. B} 75, 052103(2007). \\[0pt] [3] A.Y. Ramos et al., \textit{J. Phys. Conf. Ser}. 190, 012096 (2009). \\[0pt] [4] A. Yamasaki et al., \textit{Phys. Rev. Lett.} 96, 166401 (2006). \\[0pt] [5]J. D. Fuhr et al., \textit{Phys. Rev. Lett.} 100, 216402 (2008). \\[0pt] [6] M. Baldini et al.\textit{, Phys. Rev. Letter} 106, 066402 (2011).