Ion beam sputtered nanostructured semiconductor surfaces as templates for nanomagnet arrays

The ongoing tendency for increasing the storage densities in magnetic recording techniques requires a search for efficient routes to fabricate and characterize nanomagnet arrays on solid supports. Spontaneous pattern formation in semiconductor heteroepitaxy or under ion erosion of semiconductor surfaces yields nanostructured substrates that can serve as templates for subsequent deposition of magnetic material. The nanostructured morphology of the template can easily be replicated into the magnetic coating by means of the shadow deposition technique which allows one to selectively cover specific areas of the template with magnetic material. Here, we demonstrate that ion bombardment induced hexagonally arranged GaSb dots are suitable templates for fabricating by shadow deposition close-packed nanomagnets with a lateral extension of ≤50 nm, i.e. with a resulting storage density of up to 0.2 Tbit in(-2). Magnetic-force microscopy (MFM) measurements revealed that the individual nanomagnets-which are located on the tops of the semiconductor hillocks-are single domain and show mainly independent magnetization. The coupling behaviour was estimated from correlation function analysis of the MFM data. In addition, magneto-optical Kerr effect measurements demonstrate that the nanomagnets can be magnetized either out-of-plane or in-plane and show remanence at room temperature, with a coercive field of 120 mT.