Nanotech 2010

Electron instabilities in nanoclusters, nanostructures and inhomogeneous nanomaterials: bottom up approach

A. Kocharian
California State University, Los Angeles, US

Keywords: nanomaterials, nanoclusters, charge, spin pairings, superconductivity, magnetism


Inhomogeneous nanomaterials with strong local electron correlations are creating a new world-view in condensed matter physics [1-4]. These materials with intrinsic ihomogeneities have electronic and magnetic properties that are widely different from the conventional materials. Two prominent examples are the high temperature superconductors (HTSCs) and colossal magnetoresistance (CMR) materials. The superconductivity, ferromagnetism and ferroelectricity all are quantum phenomena occurring on a mcro- and macroscopic scales also in these nanomaterials. Rigorous conditions are found for confined electrons in clusters, obeying to Fermi statistics, by forming the pairs and undergoing statistical transformation through charge and spin pairing instabilities [5]. The electron pairs in ensemble of clusters complying to the Bose-Einstein statistics and, being in a phase, are condensed in inhomogeneous media and transferred without resistance. The recently developed “bottom up” approach displays the physics of the macro world projected to small size systems [5]. The studies of electron instabilities evolving exact model calculations in small nanoclusters establish the relationship between the micro and macro physics. The phase diagrams for ensemble of octahedral and tetrahedral clusters display a number of inhomogeneous, coherent and incoherent phases and pairing modulations seen recently in high TC cuprates, manganites and CMR nanomaterials using scanning tunelling microscopy. Our exact cluster studies have strong impact and immediate applications to nano systems (nanotechnology) can motivate interest to electronic and magnetic instabilities in novel nanoclusters and nanomaterials of correlated materials. As we shall see [5-9], certain features in contrasting topologies (octahedrons, tetrahedrons, etc) are quite different and these predictions could be exploited in the nanoscience frontier by synthesizing clusters or nanomaterials with unique magnetic and electronic properties. References [1] S. Y. Wang, J. Z. Yu, H. Mizuseki, Q. Sun, C. Y. Wang, and Y. Kawazoe, Phys. Rev. B70, 165413 (2004). [2] Y. Kohsaka et. al., Science 315, 1380 (2007). [3] T.Valla et. al., Science 314, 1914 (2006). [4] K. K. Gomes et. al., Nature 447, 569 (2007). [5] A. N. Kocharian, G. W. Fernando, K. Palandage, and J. W. Davenport, Phys. Rev. B78, 075431 (2008); ibid B74, 024511 (2006). [6] A.N. Kocharian, G.W. Fernando, K. Palandage, and J.W. Davenport, Ultramicroscopy 109, 1066 (2009). [7] A. N. Kocharian, G. W. Fernando, K. Palandage, and J. W. Davenport, Phys. Lett. A373, 1074 (2009); ibid A364, 57 (2007); [8] G. W. Fernando, A. N. Kocharian, K. Palandage, T. Wang, and J. W. Davenport, Phys. Rev. B75, 085109 (2007); ibid B80, 014525 (2009) [9] K. Palandage, G. W. Fernando, A. N. Kocharian, and J. W. Davenport, J. Comput.-Aided Mater. Des. 14, 103 (2007).
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