Feedback control of noise in spin valves by the spin-transfer torque

The miniaturization of magnetic read heads and random access memory elements makes them vulnerable to thermal fluctuations. We demonstrate how current-induced spin-transfer torques can be used to suppress the effects of thermal fluctuations. This enhances the fidelity of perpendicular magnetic spin valves. The simplest realization is a dc to...

Magnetic materials and devices for integrated radio-frequency electronics

The effect of a neighboring metal layer on the high-frequency characteristics of a thin magnetic stripe

The spin-wave spectrum of a ferromagnetic stripe placed above a metallic layer with finite conductivity is studied by using the magnetostatic Green’s function formalism. It is shown that the frequency and linewidth of the resonances are uniquely determined by complex, mode-dependent demagnetization factors. The formalism developed is used to...

Electrically detected ferromagnetic resonance

We study the magnetoresistance properties of thin ferromagnetic CrO2 and Fe3O4 films under microwave irradiation. Both the sheet resistance ? and the Hall voltage VHall characteristically change when a ferromagnetic resonance (FMR) occurs in the film. The electrically detected ferromagnetic resonance (EDFMR) signals closely match the...

Shape-induced ultrahigh magnetic anisotropy and ferromagnetic resonance frequency of micropatterned thin Permalloy films

Magnetic anisotropy Hk>200?Oe was observed from bar-shaped Permalloy strips. The film was deposited on sputtered Cr seed layer by electroplating under ? 800?Oe external magnetic field. Tiny degradation of Hk was observed after 30 min postannealing at 400?°C in the absence of external magnetic field. The Permalloy strip with in-plane aspect ratio...

Magnetic properties of electroplated nano/microgranular NiFe thin films for rf application

A granular NiFe thin film with large in-plane magnetic anisotropy and high ferromagnetic-resonance frequency developed for radio-frequency integrated circuit (IC) applications is presented. During the deposition, three-dimensional (3D) growth occurs, yielding NiFe grains (? ? 1.0??m). Nanonuclei (? ? 30–50?nm) are observed in single NiFe grains...

Magnetovibrational coupling in small cantilevers

A nanomagnetomechanical system consisting of a cantilever and a thin magnetic film is predicted to display magnetovibrational modes, which should enable applications for sensors and actuators. The “polaritonic” modes can be detected by line splittings in ferromagnetic resonance spectra.