Journal of Magnetism and Magnetic Materials 214 (2000) 225 } 233 Investigation of the response of a new amorphous ferromagnetic MFM tip coating with an established sample and a prototype device G.P. Heydon, W.M. Rainforth, M.R.J. Gibbs*, H.A. Davies, J.E.L. Bishop, J.W. Tucker, S. Huo, G. Pan, D.J. Mapps, W.W. Clegg Shezeld Centre for Advanced Magnetic Materials and Devices, University of Shezeld, Shezeld, UK Department of Engineering Materials, University of Shezeld, Shezeld S1 3JD, UK Department of Physics & Astronomy, University of Shezeld, Shezeld, S3 7RH, UK CRIST, School of Electronic, Communication and Electrical Engineering, University of Plymouth, PL4 8AA, UK Received 4 November 1999; received in revised form 8 February 2000 Abstract A new type of amorphous ferromagnetic MFM tip coating has been used to obtain high-resolution images of domain wall structures in a magnetically soft amorphous thin "lm and a prototype recording head. The new tip coating has a composition close to that of commercial METGLAS2605SC (FeSiBC) amorphous ribbon and is produced by RF-sputtering on to Nanosensors Si probes. A cross-tie wall found in an amorphous alloy thin "lm of composition Co  Nb  Zr  (at%) was taken as an established sample. Detailed study of the periodicity of the main wall, and features of the sub-structure under a variety of tip conditions, established the robustness of the images obtained. This is an important step in the use of MFM on soft magnetic materials. For comparison, images of the same section of cross-tie wall have been obtained with a commercial CoCr tip, showing an unacceptable degree of image perturbation. Having established the conditions for robust imaging, a prototype recording head produced from two layers of Co  Nb  Zr  with an SiO  isolation interlayer was successfully imaged by MFM. A classic closure domain structure adjacent to the gap was observed, in conjunction with pinned walls along the edges of the device where the etching is imprecise.  2000 Elsevier Science B.V. All rights reserved. Keywords: Magnetic force microscopy; Domain wall structures; Thin "lms 1. Introduction Soft magnetic thin "lms are being developed for a variety of applications including magnetic record- * Corresponding author. Tel.: #44-114-222-4261; fax: #44- 114-222-4261. E-mail address: m.r.gibbs@she$eld.ac.uk (M.R.J. Gibbs). ing heads. In order to understand and exploit their magnetic properties it is important to investigate magnetic domain structures in these "lms. The magnetic characterisation of such "lms is di$cult, as many of the standard probes rely on electron transparency ("lm plus substrate no thicker than 90 nm), or have limited spatial resolution (e.g. Kerr microscopy which is optical di!raction limited). This work reports images of cross-tie walls in an 0304-8853/00/$ - see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 - 8 8 5 3 ( 0 0 ) 0 0 0 4 8 - 2