National Synchrotron Light Source Seminar

As conventional magnetic recording technology extends to ever higher areal density, it is possible the often predicted, and constantly increasing, density limit will be reached. This limit will likely be in the range of 750 – 1000 Gb/in2. The use of nanofabrication to create patterned magnetic elements, or patterned media, is one of the proposed approaches with the promise of delaying the onset of superparamagnetism and thus enabling higher areal density. I will discuss many of the challenges that must be overcome for patterned media to be successful, including fundamental physics and material science issues, new fabrication technologies, nm-scale manufacturing tolerances, and low cost budgets.

One of these challenges is to controllably reverse one magnetic element, or bit, without affecting the neighboring elements. A narrow anisotropy distribution will be required, yet data suggest that as the element size shrinks, the distribution widens. This distribution arises from a number of sources, including shape and size distributions, edge effects, variations in the full film anisotropy and magnetostatic fields from neighboring elements.

In the second part of the talk, I will discuss recent work on spin torque devices, and in particular on the influence of injected rf currents on the magnetization reversal dynamics. We find that the pre-switching free layer precessional orbits can be frequency locked to the injected rf currents, and in this manner the critical dc switching currents can be either increased or decreased. Speculation on the application of such effects for high density solid state storage will be discussed.