The Problem

The antiferromagnetic (AF) alloy Iridium Manganese (IrMn) is now widely used in all spin electronic devices –  including hard disk drives and next-generation magnetic memories. Unfortunately, iridium is such a rare metal – twice as rare as gold in the earth’s crust – that relying on it for such a key future technology represents a very high risk strategy.

The price of iridium has risen by a factor of four in the last five years and by more than a factor of ten in the last decade. It is expected to soar perhaps by a factor of 100 due to its wider applications, as it is widely recognised that spin electronic technologies will displace volatile semiconductor memory technology within the next decade. Therefore the lack of availability of one crucial element from within the periodic table is a critical issue to be solved urgently.

Our research programme will impact this key material directly by providing an improved understanding of a wide ranging class of ternary alloys, and we will seek to find new materials and new compositions of Heusler Alloys to replace the need for iridium in spin electronic devices.

We therefore aim to replace iridium to reduce the cost of an AF film by a factor of 10 as compared with the current IrMn. We will combine our expertise in ab initio calculations and HA film growth techniques to seek highly anisotropic AF HA films. These films will be characterised both structurally and magnetically using synchrotron beamlines, high-resolution (scanning) transmission electron microscopy and highly sensitive electrical and magnetic measurement facilities available within the consortium.

We will demonstrate a device concept with the developed AF HA films at the end of this project, showing an exchange bias greater than 1 kOe in sheet form and a blocking temperature greater than 300K. The developed AF HA films will be patented, with the royalties shared equally among the partners in the consortium.

To our knowledge, we are the first group to realise the criticality of the position with regard to the supply of iridium.