Occurrence of two amorphous phases in an Fe40Co40B20 alloy

摘要

A process for the preparation of amorphous alloys is introduced to realize physical properties, which could not previously be achieved when using known methods. The method of preparation is based on the sputtering of metal-metalloid alloys on a substrate. Unlike presently known steady sputtering techniques, in this method of preparation, the shutter that is located between substrate and target frequently interrupts the plasma between the target and the substrate. Thereby, it possible to create interfaces, different phases, and defects between the layers, which leads to drastic change in the physical characteristics of the sample. In order to demonstrate the effect of interfaces on the magnetic parameters, an amorphous Fe40Co40B20 alloy with a thickness of 200 nm was prepared by repeated interruption of plasma between the target and the substrate. The interruption of plasma took place after the growth of each 2 nm amorphous film (8 atomic layers). It means that for the preparation of an amorphous Fe40Co40B20 alloy with a thickness of 200 nm, the plasma has to be interrupted 100 times. Each interruption duration was 30 s. The X-Ray MicroDiffraction measurements confirm the formation of amorphous structures. The analyses of Conversion Electron Mossbauer Spectroscopy, Transmission Electron Microscopy (TEM), and magnetization measurements show that the sample is amorphous. As the result of the interruption, the structure of the amorphous alloy is affected. An interesting result of this kind of preparation is the occurrence of two amorphous states or atomic arrangements of amorphous Fe40Co40B20, which leads to two different magnetic hyperfine field distributions. The TEM image shows that the formation of two amorphous states is coherent. It means that the two states are connected together without the formation of grain boundaries or interfaces. (C) 2015 Elsevier B.V. All rights reserved.