Isao Endo

Magnetic properties of compressed amorphous powder cores and their application to a fly-back converter

Fe-based amorphous powder cores with glass binder were fabricated by hot-pressing techniques. The cores exhibited low core losses, relatively low effective permeability and high flux density, which are superior magnetic properties when applied to choking coil or fly-back transformers operating in the high frequency range. The core obtained was applied to a fly-back converter working at 100 kHz. The conversion efficiency examined at output power up to 300 W was higher than that of converters using a typical commercial Sendust core and a single gap ferrite core.

Segregation structure of bias-sputtered CoCr/Cr and CoCrTa/Cr films

The dependence of the fine Cr segregation structure in CoCr/Cr and CoCrTa/Cr films on negative bias voltage (V/sub B/) is examined with a high resolution scanning electron microscope. The relationship between the structure and the magnetic properties is discussed. The Cr segregation in the grains is enhanced by a bias voltage of up to -90 V, resulting in an increase in H/sub C/ and M/sub S/. Further increasing V/sub B/ results in the homogeneous distribution of Cr in the grains and an enhancement of the Cr segregation to grain boundaries from the inside of grains and the Cr underlayer. Such microstructural change causes a decrease in M/sub S/ and an increase in H/sub C/. In the case of CoCrTa films, the effect of V/sub B/ is more pronounced than the case of CoCr films, where the Ta atoms also precipitate at grain boundaries. >

Thickness dependence of magnetic recording characteristics for C/CoCrTa/Cr thin film media

Abstract A study of the magnetic properties and recording characteristics of C/CoCrTa/Cr film media as a function of CoCrTa thickness ( t Co ) is presented. The coercivity ( H c ) shows a broad peak around 250 A, but the B r δ product decreases linearly with CoCrTa thickness. The signal-to-noise (S/N m ) gives a broad maximum at about 400 A, corresponding to which the δM half-peak width derived from the δM measurement also shows a peak. The overwrite (OW) shows a thickness-independent maximum between t Co = 200 and 400 A. By separating the effects of thickness and coercivity, it was found that H c determines mainly the S/N m when t Co is below 400 A. But OW strongly depends on both t Co and Hc .