Magnetic Nanoparticle Interactions: From Magnetostatics to Exchange

Sara A. Majetich, Carnegie-Mellon University, DMR 0804779

Undergraduate Steve Aro studied FePt nanoparticles during the 2010-2011 school year. In addition to synthesizing nanoparticles, he learned to use x-ray fluorescence to determine the Fe:Pt ratio in the resulting alloy, which determines the ability to obtain L10 ordering through the sample.

Steve graduated in May 2011 and will be spending a year in Australia as a Fulbright Fellow, prior to starting graduate school in Materials Chemistry at Penn State.

Schlenk line synthesis of nanoparticles

Magnetic Nanoparticle Interactions: From Magnetostatics to Exchange

Sara A. Majetich, Carnegie-Mellon University, DMR-0804779

We have developed a general method to form crystallographically oriented nanoparticle arrays by pattern transfer into a thin film using methanol-based reactive ion etching (RIE). This method makes it possible to pattern many types of magnetic metals that have previously required ion milling to fabricate patterns. RIE is much gentler, and is a promising technology for small feature sizes.

The TEM image shows an array of 12 nm diameter, 5 nm thick FePt dots on MgO. Below is a comparison of hystersis loops for the unpatterned FePt film, for arrays of 26 nm FePt dots with 30 nm pitch, and for 12 nm dots with 14 nm pitch.