Microwave assisted switching in Ni81 Fe19 elements

Abstract

In this study quasi-static switching behavior of a Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">81</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sub> ellipsoid (long axis 160mum, short axis 80mum, thickness 10 nm) under the influence of a microwave field by longitudinal magneto-optic Kerr effect magnetometry. The external quasi-static magnetic field is applied parallel to the long axis of the ellipsoid. The uniaxial anisotropy induced during the growth process is also orientated parallel to the long axis of the ellipsoid. The switching behavior of the Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">81</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sub> element is studied by measuring hysteresis curves with an applied microwave field perpendicular to the quasi-static magnetic field. The frequency of the microwave field was varied in the range of 500 MHz to 2.0 GHz in steps of 100 MHz. The microwave power is increased from 3.2 mW to 3.2 W for each frequency, which can be estimated as a field range from 0.2 Oe (3.2 mW) to 7.3 Oe (3.2 W). A strong reduction of the coercive field from 4 Oe to 0.5 Oe is observed in the microwave field range from 2.9 Oe (501.2 mW) to 7.3 Oe (3.2 W) for microwave frequencies between 700 MHz and 900 MHz.