Postorino, P. ; Congeduti, A. ; Dore, P. ; Sacchetti, A. ; Gorelli, F. ; Ulivi, L. ; Kumar, A. ; Sarma, D. D. (2003) Pressure tuning of electron-phonon coupling: the insulator to metal transition in manganites Physical Review Letters, 91 (17). 175501_1-175501_4. ISSN 0031-9007
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Official URL: http://prl.aps.org/abstract/PRL/v91/i17/e175501
Related URL: http://dx.doi.org/10.1103/PhysRevLett.91.175501
Abstract
A comprehensive understanding of the physical origin of the unique magnetic and transport properties of A1−xA'xMnO3 manganites (A= trivalent rare-earth and A'= divalent alkali-earth metal) is still far from being achieved [1, 2, 3]. The complexity of these systems arises from the interplay among several competing interactions of comparable strength. Recently the electron-phonon coupling, triggered by a Jahn-Teller distortion of the MnO6octahedra, has been recognised to play an essential role in the insulator to metal transition and in the closely related colossal magneto-resistance [3]. The pressure tuning of the octahedral distortion gives a unique possibility to separate the basic interactions and, at least in principle, to follow the progressive transformation of a manganite from an intermediate towards a weak electron-phonon coupling regime. Using a diamond anvil cell, temperature and pressure-dependent infrared absorption spectra of La0.75Ca0.25MnO3 have been collected and, from the spectral weight analysis [4], the pressure dependence of the insulator to metal transition temperature TIM has been determined for the first time up to 11.2 GPa. The TIM(P) curve we proposed to model the present data revealed a universality character in accounting for the whole class of intermediate coupling compounds. This property can be exploited to distinguish the intermediate from the weak coupling compounds pointing out the fundamental differences between the two coupling regimes.
Item Type: | Article |
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Source: | Copyright of this article belongs to The American Physical Society. |
ID Code: | 46241 |
Deposited On: | 02 Jul 2011 13:56 |
Last Modified: | 18 May 2016 02:12 |
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