Performance of Tunable Magnetic Inductors in Relation to the Magnetic Layer Thickness and an Applied Longitudinal Magnetic Field in Electrodeposition of the Magnetic Layer

Abstract

A tunable magnetic inductor based on magnetoimpedance effect, with low dc current/power consumption for continuous inductance tuning, has been reported recently. To optimize the tunability and quality factor of the tunable magnetic inductor of composite wire structure, the effects of the thickness of the magnetic layer and an applied longitudinal magnetic field in electrodeposition of the magnetic layer on the inductance and quality factor of tunable magnetic inductor have been investigated in this study. Specimens with a range of thicknesses of the magnetic coating layer were produced by electrodeposition. Also, specimens from electrodeposition in an applied longitudinal magnetic field varying from 0-600 Oe were produced. The characterization results indicate that there is a critical thickness for the coating layer, below which the tunability under a weak bias magnetic field ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ex</sub> ) is high (up to 50.6% at 100 kHz and 5.3% at 100 MHz, when <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ex</sub> is 1.7 Oe) and is proportional to the magnetic coating layer thickness <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">tm</i> , and above which the tunability under a weak bias field is low (up to 6.6% at 100 kHz and 2.5% at 100 MHz, when <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ex</sub> is 1.7 Oe) and is inversely proportional to <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">tm</i> . The variation of the quality factor follows the change of Fe% in the Ni-Fe layer, and the longitudinal field imposed during the electrodeposition amplifies such change by improving the uniformity of the plated layer. An averaged 23% increase of the quality factor was observed for specimens fabricated with imposed field at 143 Oe, and the inductance tunablity was significantly higher than previously reported results.