Estimation of thermal stability factor and intrinsic switching current from switching distributions in spin-transfer-torque devices with out-of-plane magnetic anisotropy

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Spin-transfer dynamics in spin valves with out-of-plane magnetized CoNi free layers

We have measured spin-transfer-induced dynamics in magnetic nanocontact devices having a perpendicularly magnetized Co/Ni free layer and an in-plane magnetized CoFe fixed layer. The frequencies and powers of the excitations agree well with the predictions of the single-domain model and indicate that the excited dynamics correspond to precessional orbits with angles ranging from zero to 90° as the applied current is increased at a fixed field. From measurements of the onset current as a function of applied field strength we estimate the magnitude of the spin torque asymmetry parameter ??1.5. By combining these with spin torque ferromagnetic resonance measurements, we also estimate the spin-wave radiation loss in these devices.Kavli Institute of NanoscienceApplied Science

Multiple ionization of diatomic molecules in collisions with 50-300-keV hydrogen and helium ions

Siegmann B, Werner U, Kaliman Z, Roller-Lutz Z, Kabachnik NM, Lutz HO. Multiple ionization of diatomic molecules in collisions with 50-300-keV hydrogen and helium ions. Physical Review A. 2002;66(5): 052701.Measurements of relative multiple ionization cross sections have been performed for 50-300-keV H+, D+, and He+ impact on N-2, O-2, CO, and NO molecules. Fragment ions with total charges up to Q=q(1)+q(2)=5 have been detected in coincidence using a position- and time-sensitive detector. Dependence of the cross section on the molecular orientation with respect to the ion beam is observed for all targets. The experimental data are compared with theoretical calculations based on the statistical energy deposition model