Current driven switching of magnetic layers

The switching of magnetic layers is studied under the action of a spin current in a ferromagnetic metal/non-magnetic metal/ferromagnetic metal spin valve. We find that the main contribution to the switching comes from the non-equilibrium exchange interaction between the ferromagnetic layers. This interaction defines the magnetic configuration of the layers with minimum energy and establishes the threshold for a critical switching current. Depending on the direction of the critical current, the interaction changes sign and a given magnetic configuration becomes unstable. To model the time dependence of the switching process, we derive a set of coupled Landau-Lifshitz equations for the ferromagnetic layers. Higher order terms in the non-equilibrium exchange coupling allow the system to evolve to its steady-state configuration.Comment: 8 pages, 2 figure. Submitted to Phys. Rev.

Current-Driven Magnetization Dynamics in Magnetic Multilayers

We develop a quantum analog of the classical spin-torque model for current-driven magnetic dynamics. The current-driven magnetic excitation at finite field becomes significantly incoherent. This excitation is described by an effective magnetic temperature rather than a coherent precession as in the spin-torque model. However, both the spin-torque and effective temperature approximations give qualitatively similar switching diagrams in the current-field coordinates, showing the need for detailed experiments to establish the proper physical model for current-driven dynamics.Comment: 5 pages, 2 figure

Local Probing of the Giant and Domain-Wall Magnetoresistance

Applied Science

A 72% PAE, 10-watt, CMOS-LDMOS switch-mode power amplifier for sub-1GHz application

A low-cost silicon-based high efficiency CMOS-LDMOS switch-mode power amplifier (SMPA) line-up operating for sub-1GHz application is presented. The switch-mode operated LDMOS device is driven by high-speed, high voltage driver, implemented in a standard 0.14µm CMOS process technology. The CMOS driver uses high voltage extended-drain devices and delivers a 5.0VPP output voltage swing up to 1GHz. The power stage is formed by the latest LDMOS transistor designed for base station applications. The load-pull measurement results show that the proposed SMPA line-up achieves a drain efficiency (¿) >80.5% and a power-added efficiency >72.6% from 450MHz to 1000MHz with an output power Pout >10W and a power gain > 26.5dB

RF power silicon-on-glass VDMOSFETs

Electrical Engineering, Mathematics and Computer Scienc