Thomas F. Ambrose

“All-Heusler alloy” current-perpendicular-to-plane giant magnetoresistance

A materials system of ternary full Heusler alloys exhibiting substantial current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) has been theoretically proposed and experimentally realized. Observed trends in magnetoresistance are broadly consistent with the modeling results. A CPP-GMR of 6.7% and ΔRA of 4 mΩ μm2 have been demonstrated in the bottom spin-valve configuration. The spin-stand testing of narrow-track recording heads confirmed compatibility of these materials with hard disk drive reader technology.

Fast Magnetization Switching With Circularly Polarized Fields and Short Pulses

In this paper, we study the magnetization reversal process of single-domain Stoner-Wohlfarth particles subject to circularly polarized fields and short pulses using analytical and numerical models. We investigate the effect of short unipolar, bipolar field, and circularly polarized field pulses, which are applied perpendicular to the uniaxial magnetocrystalline anisotropy axis, on the magnetization switching dynamics.

High Anisotropy Y-Co Films on Thin Cu Underlayer

The role of Cu underlayer for preparing CaCu5-type high magnetic anisotropy YCo5 phase was studied. We prepared the Cu/YCo structure with a DC magnetron sputtering deposition system under elevated substrate temperatures. We successfully produced magnetic films which contains a high-Ku Y(Co, Cu)5 phase using a 7.5-nm-thick Cu underlayer, and under the growth temperature of 470 degC and above. The film has the perpendicular c-axis orientation with spread of 3deg. At 470 degC growth temperature, the film consists of a crystalline Cu-rich Y(Co, Cu)5 phase and an amorphous Co-rich Y(Co, Cu)5 phase. A rather thin Cu underlayer thickness of 7.5 nm was sufficient for obtaining a good perpendicular c-axis orientation, and the high-Ku phase production