Thursday, 26 October 2006 - 9:35 AM
Holiday Inn-Douglas (Holiday Inn)
84

Synthesis and Physical Properties of Ferromagnetic Semiconducting EuO Nanorods

Matthew J. Bierman and Song Jin. University of Wisconsin, Madison, WI

We report the synthesis, structural characterization, and physical properties of nanorods of the concentrated ferromagnetic semiconductor EuO. This 1.1eV bandgap semiconductor becomes a Heisenberg ferromagnet with a bulk Tc of 69K. One-dimensional building blocks of this interesting material are being fabricated for use in spintronic devices and to investigate the physical properties of this unique material. Crystalline nanorods of Eu(OH)3 are precipitated in a facile reaction from aqueous solution, converted in a solid state reaction in air to Eu2O3, and reduced in a Eu vapor to EuO. Identity has been confirmed with powder x-ray diffraction. Nanorod morphology has been monitored with scanning electron microscopy and transmission electron microscopy. SQUID magnetometry has confirmed the ferromagnetic nature of the nanorods, and shown a Curie temperature of around 75K. The rods show a saturation magnetization of 165 emu/g at an applied field of 1.5 Tesla. Hysteresis is clearly seen below the Curie temperature. The magneto-optical properties have also been measured by Magnetic Circular Dichroism (MCD). A spin imbalance is seen in transitions associated with the 4f7->5dt2g and 4f7->5deg transitions. Both transitions exhibit pseudo-A term MCD behavior. The MCD spectra give evidence of enhanced Zeeman splitting, which shows a large MCD signal that is consistent with a ferromagnetic semiconductor.

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