Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 15: Topical Session Nanoporous Functional Materials IV

MM 15.3: Vortrag

Dienstag, 24. März 2009, 11:00–11:15, IFW B

Electrostatic Doping of Strongly Correlated Systems — •Ajay Kumar Mishra, Azad Darbandi, Robert Kruk, and Horst Hahn — Institute for Nanotechnology, Forschungszentrum Karlsruhe GmbH, P.O. Box 3640, D-76021 Karlsruhe, Germany

We present a study on the tuneable magnetic transitions using electrostatic doping (electrostatic modulation of the carrier density upon surface charging). In strongly correlated materials, like colossal magnetoresistance compounds (CMR), electrostatic doping can alter fundamental properties of the electronic system by inducing phase transitions.

Since the electrostatic doping is a surface effect a large surface-to-volume ratio is desired to get an appreciable modification of the physical properties. In order to obtain such nanostructures, La1-xSrxMnO3 (LSMO) nanoparticles were synthesized by spray pyrolysis. The microstructure of the as synthesized nanoparticles consists of porous, shell-like structures with a particle size of about 8 nm. The magnetic measurements of nanoparticles show superparamagnetic behavior at room temperature. A controlled post annealing was carried out to bring the ferromagnetic transition slightly above room temperature. The sharp transition and favorable surface-to-volume ratio is reached at annealing temperatures between 800-1100 0C, resulting in grain sizes ranging from 30 to 80 nm. A reversible change of 2 % in magnetization is observed when the charge is applied at the solid-electrolyte interface. The magnetization modulation upon charging is discussed in terms of the reversible electrostatic hole doping.

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