Y. Ding — Page 49 | Search arXiv

arXiv2006

A Thermal Beam of Metastable Krypton Atoms Produced by Optical Excitation

A room-temperature beam of krypton atoms in the metastable 5s[3/2]2 level is demonstrated via an optical excitation method. A Kr-discharge lamp is used to produce VUV photons at 124 nm for the first-step excitation from the ground-level 4p6 1S0 to the 5s[3/2]1 level. An 819 nm Ti:Sapphire laser is used for the second-step excitation from 5s[3/2]1 to 5p[3/2]1, followed by a spontaneous decay to the 5s[3/2]2 metastable level. A metastable atomic beam with an angular flux density of 3 x 10^14 /s/sr is achieved at the total gas flow rate of 0.01 cm^3 STP/s (or 3 x 10^17 atoms/s). The dependences of the flux on the gas flow rate, laser power, and lamp parameters are investigated.

physics.atom-ph↗

arXiv2004

Current induced magnetization dynamics in current perpendicular to the plane spin valves

We observe magnetization dynamics induced by spin momentum transfer in the noise spectra of current perpendicular to the plane giant magnetoresistance spin valves. The dynamics are observable only for those combinations of current direction and magnetic configuration in which spin transfer acts to reorient the free layer magnetization away from the direction set by the net magnetic field. Detailed measurements as a function of magnetic configuration reveal an evolution of the noise spectra, going from a spectrum with a well-defined noise peak when the free layer is roughly collinear with the pinned layer to a spectrum dominated by 1/f noise when the free layer is in an orthogonal configuration. Finally, the amplitude of the corresponding resistance noise increases rapidly with increasing current until it saturates at a value that is a substantial fraction of the magnetoresistance between parallel and antiparallel states.

cond-mat.mtrl-sci↗