Strain-Free All Heusler Alloy Junctions

Introduction

Spintronics is anticipated to replace current semiconductor-based memories and sensors based on fast-operating times (< ns) and low power consumption (< pJ per read/write operation). The spintronic devices typically consist of a magnetoresistive junction with a free ferromagnet/oxide barrier or non-magnet/pinned ferromagnet trilayer and may suffer from edge-domain formation and leakage current through the barrier by further miniaturisation (<10 nm in cell diameter).

Challenges in Spintronics

To avoid such obstacles, antiferromagnetic spintronics has recently been developed by introducing spin-orbit torque, which can reduce the power consumption by over two orders of magnitude but contains critical raw materials.

Project Objective

In this transformative project, we aim to develop a ferrimagnetic Heusler-alloy film, in which the magnetic properties will be controlled by substituting the constituent element to achieve compensated ferrimagnetism (effectively the same as antiferromagnetism) sandwiched by weak and strong ferrimagnet in a single-step deposition.

Methodology

This will be achieved based on our Heusler-alloy database developed recently through existing collaborations. The selected alloy(s) without using critical raw materials will be:

1. Grown by dedicated combinatorial sputtering under low pressure.
2. Characterised by conventional structural and magnetic analysis.
3. Assessed using non-destructive imaging we have developed and synchrotron-beam imaging at the Paul Scherrer Institute.

Expected Outcomes

Such atomic engineering can offer a new way for material development for low-power electronics. The simplified growth process for a junction without any interfacial scattering is adoptable for future spintronic devices as will be demonstrated using the 200-mm-wafer production line at IMEC by the end of this project.

Conclusion

Hence, this proposed project will reveal both fundamental magnetic coupling in a ferrimagnetic alloy and atomic control of the alloy for new growth processes, which can revolutionise spintronic device production.