hide
Free keywords:
-
Abstract:
The quarternary substitutional series Co2Cr1-xFex Al was investigated by
means of surface and bulk sensitive techniques in order to exploit its
structural and compositional properties. Both bulk and powder samples of
the alloy series were investigated to obtain specific information about
this material.
The long range order was determined by means of x-ray diffraction and
neutron diffraction, while the site specific ( short range) order was
proved by extended x-ray absorption fine structure spectroscopy. The
magnetic structure was investigated by Mossbauer spectroscopy in
transmission and scattering modes in order to compare and separate
powder and bulk properties. The chemical composition was analysed by
means of x-ray photo emission spectroscopy combined with Auger electron
spectroscopy depth profiling. The results from these methods are
compared to get an insight into the differences between surface and bulk
properties and the appearance of disorder in such alloys.
The material shows an extremely high sensitivity to oxygen. In
particular, powder materials show a high amount of oxygen contamination.
Therefore, an additional oxide-mediated tunnel magneto-resistance may
always contribute to measurements of magneto-resistive effects because
the oxide layers will provide natural tunnelling barriers. In addition,
the results suggest that thin films have to be produced under ultra-high
vacuum conditions.
