Colossal magnetoresistance manganites: A new approach

Journal of Chemical Sciences

H R Krishnamurthy1 2¹  S R Hassan1¹  T V Ramakrishnan1¹  G Venketeswara Pai1¹ 

[1] Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560 012, India$$

关键词: Manganites;    colossal magnetoresistance;    strongly correlated electron systems;    metal-insulator transitions and other electronic transitions;    Jahn-Teller polarons and electron-phonon interaction.;   

DOI  :  

来源: Indian Academy of Sciences

【 摘 要 】

Manganites of the LA1-𝑥Ca𝑥MnO3 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 𝑒𝑔 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.

【 授权许可】

Unknown