Nanocomposite Oxide Thin Films For Novel Ionotronic Magnetoelectrics

Lead Research Organisation: University of Cambridge
Department Name: Materials Science & Metallurgy

Abstract

Ionotronic devices rely on charge effects based on ions instead of/or in addition to electrons. The field has begun to gain very wide attention recently. It has been applied mainly to oxide thin film memristors (resistance depends on voltage and can be switched between an 'on' and an 'off' state of high and low resistance). These devices are interesting for creating electrically switchable memory, but there are challenges with these structures including the requirement of a setting process and variable properties from one film to another.

In this proposal, we have the new idea to utilise ionotronic effects to create a new kind of electrically switchable memory. Here ionic defects at vertical interfaces in vertical nanocomposite thin films charge couple to magnetism in a magnetic transition metal oxide. Since the cation valences in the metal oxide depend on oxygen concentration or charge state, and since the magnetic properties depend on cation valences, it should be possible to switch magnetism on and off by applying an electric field. This device is an ionotronic magnetoelectric, and it represents a completely new form of magnetoelectric RAM.

Magnetoelectric RAM is where electric field controls magnetism instead of electric current doing so as in other forms of RAM, and it is a long sought-after goal. It offers the possibility of low power, very high density, high-speed reading and writing times, and non-volatility. Low energy, high performance computing is promised with this technology. However, while a range of structures and materials have been studied to date, none has proved practical in terms of ease of structure formation, stability, temperature of operation, or size of magnetoelectric effect.

Making the ionotronic magnetoelectric a practical reality is not trivial, and relies on advanced materials science - the growth of very thin films, the creation of highly ordered materials combinations on a very small scale (1/0000 the thickness of a human hair), the movement of charges along interface nanochannels near to room temperature, the knowledge of which materials combine together in a compatible way, the imaging of materials at the atomic scale, etc. To attain the 'practical magnetoelectric' dream we propose to create and measure new structures, we will use unique experimental capabilities and will also collaborate with world-leading researchers. Our starting point for the research is our ability to create, at the nanometre scale, ionic interface channels in perfect vertical nanocomposite films. We have also observed the first signs that ions can indeed charge couple to magnetic properties.

Planned Impact

This research has both fundamental and applied aspects. On a fundamental level we are exploring a new paradigm in thin film materials design and nanostructuring. We aim to develop a plug-in approach for designing new systems in the future. The impact here will be the generation of knowledge in an entirely new area which could have long-term societal and economic benefits.

There are also applied aspects to our work. Our main thrust is to demonstrate devices with properties above and beyond what can be generated by any other means. Examples are that we have recently patented a high performance, non-forming process, high retention memristor nanocomposite device. We are now aiming to move well beyond this, to create a practical magnetoelectric device. These systems have potential in new types of fast, low power consumption computer memory. We will patent actively in the area and seek external licensors. We have a very good track record in getting patents licensed. There is clear economic impact from patent licensing. We will also liaise closely with 2 industries (Deregallera, UK, and Applied Materials, USA and Germany) who are keen to be involved in the project.

As far as societal impact goes, we will generate highly skilled technical researchers within an international training environment. Cambridge is a high tech. hub with many job openings for technically skilled people. Our trained researchers have gone to both local companies and international ones. Also, several of our researchers have got good jobs in academia in the UK and EU. This proposal will allow us to keep feeding excellent researchers into companies and academia which will have direct benefit to UK society and the knowledge economy.

Publications

10 25 50
 
Description We have determined that we can achieve a strong magnetoelectric effect in nanocomposite films incorporating ionic and magnetic phases in a single, self-assembled film. A direct electric field manipulation of magnetism in a practical film has not be achieved before. We are in the process of preparing papers and on further understanding and developing demonstrator devices
Exploitation Route It may be used in practical magnetoelectric RAM, but this will not happen right away.
Sectors Electronics

 
Description EMA conference in Florida, January 2017 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Talk given.
Year(s) Of Engagement Activity 2016
 
Description Fall MRS Conference, Boston, 2016 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Talk given on the research from this proposal
Year(s) Of Engagement Activity 2016