Ju Hun Lee

TMR of double spin-valve type AF/FM/I/FM/I/FM/AF magnetic tunneling junctions

An unusually large enhancement of TMR at 77 K was observed in double barrier tunnel junctions (DBTJ). This is explained with extended Jullieres model which yields a twice larger TMR value. When the spin coherence length is much smaller at higher temperature, DBTJ is shown to work as a series of two single barrier tunnel junctions.

Synthesis and Characterization of

We report the synthesis and characterization of Fe-FeOx core-shell nanowires by thermal conversion of the Fe nanowires from pulse electrodeposition in anodized aluminum oxide (AAO) nanotemplates under various conditions. Well-defined core-shell nanostructure of the Fe-FeOx nanowires was confirmed by TEM and corresponding elemental line scanning and point scanning. The type of the iron oxide in the shell was identified using nano-Raman spectroscopy, which exposes magnetite to be the major constituent. The magnetic measurements demonstrate that the nanowires are robustly soft magnetic, with the magnetization tunable by heat treatment parameters and a weak magnetic easy direction parallel to the nanowire axis.

{\rm Fe-FeO}_{\rm x}

Au-doped CoPt nanowires were prepared in anodized aluminum oxide (AAO) nanotemplates by electrodeposition and the doping effects on their microstructure and magnetic properties were investigated. Dependent on the deposition conditions, the CoPtAu nanowires can have the cubic or tetragonal phase. The magnetic measurements indicate that the nanowires demonstrate ferromagnetic behavior, showing the easy axis along the direction of the nanowires and strong enhancement in coercivity and squareness prior to annealing, whereas the optical measurements reveal plasmon resonances characteristic of nanostructured Au.