An international team of researchers have for the first time, discovered that in a very high magnetic field an electron with no mass can acquire a mass. Understanding why elementary particles e.g. electrons, photons, neutrinos have a mass is a fundamental question in Physics and an area of intense debate. This discovery by Prof Stefano Sanvito, Trinity College Dublin and collaborators in Shanghai was published in the prestigious journal Nature Communications this month.
While the applications of this discovery remain to be seen, this represents a significant breakthrough in fundamental physics. It could inspire work in high-energy physics, such as the collision experiments carried out in particle accelerators like CERN. This is the third joint publication between the group in Trinity and Prof. Faxian Xiu at Fudan University in Shanghai, who approached Prof Sanvito to provide theory support for their experimental activity based on his previous publications and international reputation in the field of theoretical physics.
Prof Stefano Sanvito, Principal Investigator at the Science Foundation Ireland funded AMBER (Advanced Materials and BioEngineering Research) centre based at Trinity and the CRANN Institute and Professor in Trinity’s School of Physics said, “This is a very exciting breakthrough because until now, nobody has ever discovered an object whose mass can be switched on or off by applying an external stimulus. Every physical object has a mass, which is a measure of the object’s resistance to a change in its direction or speed, once a force is applied. While we can easily push a light-mass shopping trolley, we cannot move a heavy-mass 6-wheel lorry by simply pushing. However, there are some examples in Nature of objects not having a mass. These include photons, the elementary particles discovered by Einstein responsible for carrying light, and neutrinos, produced in the sun as a result of thermonuclear reactions. We have demonstrated for the first time one way in which mass can be generated in a material. In principle the external stimulus that enabled this, the magnetic field, could be replaced with some other stimulus and perhaps applied long-term in the development of more sophisticated sensors or actuators. It is impossible to say what this could mean, but like any fundamental discovery in physics, the importance is in its discovery.”
He continued, “It has been very satisfying to continue to work with Prof Xiu in Shanghai. While his group are experts in growing and characterizing materials such as ZrTe5 which are very difficult to make, my group has the expertise in the theoretical interpretation. The measurements were carried out in Fudan and at the Wuhan National High Magnetic Field Center in China, while the Dublin team provided the theoretical explanation for the finding. This has been a very fruitful collaboration and we have a number of other publications in progress”.
The team studied what happened to the current passing through the exotic material zirconium pentatelluride (ZrTe5) when exposed to a very high magnetic field. Measuring a current in a high magnetic field is a standard way of characterising the material’s electronic structure. In the absence of a magnetic field the current flows easily through ZrTe5. This is because in ZrTe5 the electrons responsible for the current have no mass. However, when a magnetic field of 60 Tesla is applied (a million times more intense than the earth’s magnetic field) the current is drastically reduced and the electrons acquire a mass. An intense magnetic field in ZrTe5 transforms slim and fast electrons into fat and slow ones.
Researchers in AMBER, the Science Foundation Ireland funded materials science centre, hosted in Trinity College Dublin, have created a simpler process to produce germanium-tin nanowires (germanium is a semiconductor with superior electronic properties compared with silicon). The research breakthrough recently published in the prestigious scientific journal Nature Communications describes this new process as essential in potentially enabling the production of an entirely new generation of faster, smaller and greener electronic devices.
The research team at AMBER have successfully fabricated highly crystalline, germanium–tin nanowires. The nanowires were grown from a simple, cheap and scalable gas-phase process employing a unique combination of chemical reactions developed by the AMBER team in Ireland. Importantly, the nanowires produced are expected to lead to electronic devices that are up to 125 times more power efficient than conventional devices due to the unique electrical properties of germanium-tin, ultimately resulting in smarter and greener electronic gadgets, such as mobile phones, tablets, sensors and smart watches.
Professor Justin Holmes, Investigator at AMBER and Professor of Nanochemistry at University College Cork, said: “This is a significant advancement in the field of nanostructure research and opens up new possibilities for the development of future technologies. Current mobile devices based on existing technology are energy inefficient, due to high power consumption and the dissipation of a large amount of heat, leading to wasteful battery usage or the requirement for elaborate cooling systems. In the field of electronics and optics, manipulation of nanoscale structures should lead to more energy efficient phones and computers.”
Nanowires are similar to normal electrical wires but are extremely small, typically thinner than one thousandth of the thickness of a human hair. Just like normal wires, nanowires can be made from a variety of different materials, including metals such as copper and gold or semiconductors such as silicon and germanium.
Nanowires often exhibit unique optical, electrical and even mechanical properties that are not found in bulk materials, making them very attractive for a range of applications that include chemical and biological sensors, computer circuitry and light emitting diodes (LEDs). Notably, increasing the number of nanowire switches (or transistors) on a silicon chip enables the production of faster, smaller and more mobile electronic devices.
The AMBER team are currently in collaboration with industrial partners to demonstrate the commercial viability of nanowire-based energy efficient electronic and optical devices within a 5-year timeframe.
The paper can be found in full here: http://www.nature.com/ncomms/2016/160420/ncomms11405/full/ncomms11405.html
Prof. Valeria Nicolosi from AMBER, the Science Foundation Ireland funded materials science centre, hosted in Trinity College Dublin, has been announced as a recipient of the European Research Council’s (ERC) Proof of Concept Grants, worth €150,000. This is a top-up for her ERC Starting Grant of €1.5m awarded in 2011 and brings her total research funding awarded in the past 5 years, to over €12million. Prof. Valeria Nicolosi is Ireland’s only five-time ERC awardee.
The award will be used to explore the commercial use of advanced nanomaterials to act as solutions for heat dissipation for the high-end automotive industry.
Proof of Concept grants are awarded to ERC grant holders only as top-up funding to explore the commercial or innovation potential of the results of their ERC-funded research. Prof Nicolosi, Investigator with AMBER and Trinity’s School of Chemistry was awarded an ERC Starting Grant of €1.5M in 2011 for her work in processing and characterising nanomaterials for the development of novel energy storage devices. As a result of this Starting Grant, she began collaborating with a company in the automotive industry to explore the use of novel 2-dimensional nanomaterials to solve heat dissipation issues. Her technology was successful and the aim of this proposal is to determine the economic and technical feasibility of using readily scalable technologies for the development of inexpensive and high performance solutions to solve heat dissipation for a wide range of technologies.
Prof. Valeria Nicolosi, Professor at the School of Chemistry, Trinity College Dublin and Principal Investigator at AMBER, said, “I am delighted to be awarded this 3rd ERC Proof of Concept Grant which will allow me to build on the success of my technology developed from my Starting Grant. What is exciting about this work is that in addition to the automotive industry, there are a huge range of industrial applications that can benefit from more efficient and lightweight thermal management systems such as advanced aircraft, injection moulding, pharmaceutical manufacturing and household appliances. This technology has the potential to become a feasible, easy and efficient solution for a range of manufacturing companies. This grant is allowing me to take the next step with the technology to really see it applied in industry”.
Considerable industrial effort is currently focussing on finding alternative materials to act as thermal conductive elements and heat spreaders in an efficient and cost effective way. Manufacturers need these technologies to regulate the large amounts of unwanted heat caused by the normal functioning of electronic systems. It is estimated that the global market for thermal management products will grow from about $10.7 billion in 2015 to $14.7 billion by 20211. Prof Nicolosi’s technology will offer a cheap, scalable solution of using advanced 2D nanomaterials for enhanced heat transport. 2D nanomaterials improve heat transport due to their thermal conductivity properties and at the same time provide a lightweight solution. Moreover, the technology offers the advantage of being extremely versatile; 2D nanomaterial dispersions can be sprayed on their own directly onto surfaces or they can be mixed with different materials to obtain additional enhanced resistance to wear, abrasion and oxidation. This will allow manufacturers to improve the performance of existing systems, as well as improve the performance of new designs.
Prof. Michael Morris, Director of AMBER, commented on the announcement, saying, “The awarding of this Proof of Concept Grant to Prof. Nicolosi is an excellent acknowledgement of the research work she and her team are currently undergoing. She is at the forefront in 2D nanomaterials research and her work will bring economic and societal benefits to Ireland in developing more efficient ways to deal with energy consumption. During her time at Trinity, Prof. Nicolosi has received over €12 million in funding, including €6.8 million to date from the ERC, and now an additional €150,000 to further her research. She is an exceptional asset to the AMBER team and this funding also reaffirms how competitive Ireland is as a place for research.”
The budget of the overall ERC 2016 Proof of Concept competition is €20 million. In the first round of the competition 141 ERC grant holders applied and 44 received funding.
A team of physicists from the SFI funded AMBER (Advanced Materials and BioEngineering Research) Centre at Trinity College, Dublin have made a new device which could lead to a breakthrough in mass storage of digital data. Two PhD students, Yong Chang Lau from Malaysia and Davide Betto from Italy, working with senior researcher Dr Karsten Rode and Professors Michael Coey and Plamen Stamenov published their results in the prestigious journal Nature Nanotechnology earlier this Summer .
Professor Michael Coey, a Principal Investigator in AMBER and the School of Physics, Trinity College Dublin, said, ‘The flood of digital data is growing every year and new storage concepts are urgently needed to sustain the information revolution. Forecasts envisage 20.8 billion wirelessly-connected “things” throughout the world by 2020. At present, it is estimated that 5.5 million new ones are connected every day . This is a huge challenge for mass data storage, which currently relies on hard discs. Everything we download daily onto our computers or mobile phones is stored magnetically on millions of these spinning discs located in data centres scattered across the planet’.
‘One main contender for the future of mass storage is MRAM (Magnetoresistive random-access memory), under development since the 1990s. MRAM is faster and offers higher density compared to other non-volatile RAMs. A large amount of research has been carried out in developing it, but MRAM has not been widely adopted in the market yet, largely due to the costs and complexity of large scale fab manufacturing. Our team in AMBER, at Trinity College Dublin, may now have solved the problem, offering a simpler solution for manufacturing a type of MRAM.’
The team, who are made up of experts in magnetism and magnetic switching, which is at the heart of data storage, have managed to circumvent the need to use a magnetic field. Their elegant new device consists of a stack of five metal layers, each of them a few nanometers thick. At the bottom is a layer of platinum, and just above it is the iron-based magnetic storage layer just six atoms thick. Platinum is a favorite of researchers in spin electronics, the technology that makes use of the fact that each electron is a tiny magnet. Passing a current through the platinum separates the electrons into two groups with their magnetism pointing in opposite directions at the top and bottom surfaces thanks to an effect known as ‘spin-orbit torque’ that follows from Einstein’s theory of relativity. Electrons at the top are pumped into the storage layer and try to switch its magnetic direction, but like a pencil balanced on its point, the magnetism of the storage layer can’t decide which way to fall. The team designed the rest of the stack to solve that dilemma by acting like a nanoscale permanent magnet that creates the small field necessary to make the switching determinate, at zero cost in energy.
The Group now plans to demonstrate a full memory cell, and an ultra-fast oscillator based on spin-orbit torque using layers of a novel magnetic alloy they discovered recently. The device stacks will be grown in a sophisticated new SFI-funded thin film facility in the AMBER Centre at Trinity’s CRANN Institute for nanoscience. These new spintronic devices have potential to deliver the breakthrough needed to sustain the information revolution for another 25 years.
 The full paper is published online at the below link: