Introduction

Tapered structures such as pyramids and cones are commonly used in magnetic force microscopy (Dahlberg and Proksch, 1999, Sáenz et al., 1987); the phase shift induced by the movement of a cantilever attached to the structure can be interpreted to yield the stray field pattern of a sample (McVitie et al., 2001).

Part-conical samples of size order 1 $\mu\mathrm{m}$ and above have previously been fabricated for bubble devices (Sanders et al., 1981). Nanolithographically defined structures created through electron beam lithography (Chou, 1997, Chou et al., 1996) result in arrays of tapered pillars which are geometrically conical. The coercivity of arrays of shorter cones created with interference lithography has been previously investigated experimentally and numerically (Ross et al., 2001).

In this chapter, we study the magnetic reversal behaviour of cones systematically and compute a magnetisation remanence phase diagram as a function of diameter and height.