Magnetic Properties of Thermal Sprayed Tungsten Carbide–Cobalt Coatings

In the information age, the storage and accessibility of data is of vital importance. There are several possibilities to fulfill this task. Magnetic storage of data is a well‐established method and the range of materials used is continuously extended. In this study, the magnetic remanence of thermally sprayed tungsten carbide–cobalt (WCCo)‐coatings in dependence of their thickness is examined. Two magnetic fields differing in value and geometry are imprinted into the coatings and the resulting remanence field is measured. It is found that there are two effects, which in combination determine the effective value of the magnetic remanence usable for magnetic data storage.

     

Incrementally maintained network→relational database mapping

An incrementally maintained mapping from a network to a relational database is presented. This mapping may be established either to support the efficient retrieval of data from a network database through a relational interface, or as the first step in a gradual conversion of data and applications from a network to a relational database system. After the mapping has been established, the only data mapped from the network to the relational database are the increments resulting from updates on the network database. The mapping is therefore an efficient alternative to mappings that repeatedly map the results of retrievals through the relational interface from the network database to the relational database. This is in particular the case when the two databases reside on different hosts. Applications on the network database may, under certain restrictions, gradually be moved to the relational database, while the mapping incrementally maintains the relational database for the applications that remain on the network database. A detailed, but generic, account of how to build such a mapping from a network to a relational database is given, including all the algorithms needed and examples of their use.     

Magnetic microstructure analysis of sputter deposited permalloy thin films on a spin-on polyimide substrate

We have performed magneto-optical measurements of sputter deposited permalloy (NiFe 81/19) thin films on a polyimide based spin-on substrate and a silicon oxide substrate. Experiments were performed by means of the magneto-optic Kerr effect in order to complement the findings concerning soft magnetic behaviour on the macroscopic scale presented previously (Rittinger et al., Impact of different polyimide-based substrates on the soft magnetic properties of NiFe thin films, SPIE Microtechnologies. International Society for Optics and Photonics, Bellingham, pp 95171R, 2015) with new insights into the magnetic domain structures of such samples. First, magnetization curves (R–H-, B–H-curves) are compared with corresponding magneto-optical hystereses. Second, by taking into consideration the results of the magnetic microstructure analysis, further aspects of the interactions between the substrate and the functional thin film are revealed in form of analogies between observations on the microscopic scale and variations of macroscopic magnetization curves of analysed samples. Furthermore, the shape and detailed spatial arrangement of domains and their boundaries are determined for the investigated samples, supplying further information on the properties and state of stress of the thin films. Doing so, we aim to provide precise and reliable anisotropic magnetoresistive (AMR) sensors on flexible polymer substrates in the future.