A Taraphder 2007 J. Phys.: Condens. Matter 19 125218 doi:10.1088/0953-8984/19/12/125218
A Taraphder
Show affiliationsThe rich physics in the overdoped regime in colossal magnetoresistive manganites is discussed in detail. Apart from having a large magnetoresistance like its underdoped counterpart, the overdoped regime offers a rich variety of phenomena including magnetic, charge and orbital order at low temperatures. The antiferromagnetic metallic state with anisotropic carrier transport, low-dimensional magnetic states and a broad spectrum of excitations is discussed. It is argued that the physics in the overdoped regime is primarily governed by the coupling of orbitals and spins. The Jahn–Teller effect, considered to be crucial for the understanding of underdoped manganites, does not play a major role in the overdoped region. The inadequacy of the limit of infinite Hund's coupling in describing the manganites, and the importance of Coulomb correlations, are borne out in several examples described. Bilayer manganites, owing to their layered structures, are shown to have an effectively stronger coupling with the underlying structural distortions. The charge ordering close to x = 0.5 and the effect of changing bandwidth are discussed. The effect of disorder and the possibility of having an inhomogeneous mixture of competing states are also outlined.
75.47.Gk Colossal magnetoresistance
75.30.Kz Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.)
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
Issue 12 (28 March 2007)
Received 24 August 2006
Published 6 March 2007
A Taraphder 2007 J. Phys.: Condens. Matter 19 125218
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