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Colossal magnetoresistance manganites: A new approach

Ramakrishnan, TV and Krishnamurthy, HR and Hassan, SR and Pai, Venkateswara G (2003) Colossal magnetoresistance manganites: A new approach. In: Journal of Chemical Sciences, 115 (5-6). pp. 767-774.


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Manganites of the $LA_{1-x}Ca_xMnO_3$ family show a variety of new and poorly understood electronic, magnetic and structural effects. Here we outline a new approach recently proposed by us, where we argue that due to strong Jahn–Teller (JT)coupling with phonons the twofold degenerate $e_g$ states at the Mn sites dynamically reorganize themselves into localised, JT polarons l with exponentially small inter-site hopping, and band-like, nonpolaronic states b, leading to a new 2-band model for manganites which includes strong Coulomb and Hund’s couplings. We also discuss some results from a dynamical mean-field theory treatment of the model which explains quantitatively a wide variety of experimental results, including insulator–metal transitions and CMR, in terms of the influence of physical conditions on the relative energies and occupation of the l and b states. We argue that this microscopic coexistence of the two types of electronic states, and their relative occupation and spatial correlation is the key to manganite physics.

Item Type: Journal Article
Publication: Journal of Chemical Sciences
Publisher: Indian Academy of Sciences
Additional Information: The Copyright belongs to Indian Academy of Sciences.
Keywords: Manganites;Colossal magnetoresistance;Strongly correlated electron systems;Metal–insulator transitions and other electronic transitions;Jahn–Teller polarons and electron–phonon interaction
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 09 Apr 2006
Last Modified: 19 Sep 2010 04:25
URI: http://eprints.iisc.ac.in/id/eprint/6216

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