University of Wisconsin Stout | Wisconsin's Polytechnic University

Plasma-Aided Nanomagnet Control and Characterization (PANCAC)

I make nanomagnets in the PANCAC lab at UW-Stout using a technique called "gas-phase aggregation". The cartoon at left illustrates how gas phase aggregation works.  A bulk magnetic material (shown in small yellow circles in a crystal lattice) goes into a magnetron sputtering discharge (or plasma, illustrated as electrons - the empty circles, plus neutral gas atoms - the large purple circles, and positive ions of those atoms).  The bulk material is held at a negative voltage relative to the discharge.  The positive ions from the discharge slam into the bulk solid, knocking the solid more atoms into the plasma, where it becomes gas-phase.  To encourage the gas-phase atoms to aggregate into clusters, the entire region is cooled.  The cooling time restricts the size of the clusters to remain on the nanoscale.