‘I’m a little lazy’
The Spinoza Prize for Bart van Wees comes as no surprise to insiders. Van Wees is responsible for many breakthroughs in the field of quantum conductivity.
He experimentally demonstrated ‘quantisised conductivity’, which decreases the electrical conductivity in nano strings as they become thinner in steps.
In Groningen, he primarily works with spintronics. Electrons have a quantum mechanical spin, which causes them to behave like the needle of a compass.
You can use the magnets to send or receive information.
Van Wees is looking for practical applications, in particular by studying the spin in graphene, which is a layer of carbon that is one atom thick.
Spin streams can be used to cleverly combine materials with different characteristics, for example to store information, to do calculations and communicate all at once.
Reading time: 8 minutes (1,080 words)
Professor of technical physics Bart van Wees hates all the fuss. He will be happy when the Spinoza Prize ceremony is over – even though he realizes it is the crowning glory of his life’s work in nanophysics. He is honoured, of course. Especially because the competition was so fierce: ‘Nanoscience operates on a very high level in the Netherlands, so there were a lot of rivals.’
But insiders are not at all surprised at Van Wees’ win. Even when he was desperately trying to keep the news a secret – as the prize’s organiser, the research institution NWO, demands – and only told his secretary, his group sensed it immediately. How? ‘The secretary closed her door’, he says, ‘So they already knew.’
The physicist has been involved in many minor and major breakthroughs in the field. For instance, during his PhD research at the TU Delft, he was the first person to demonstrate so-called quantised conductance experimentally. This is the phenomenon where electrical conduction in nanowires gradually decreases as those wires are made thinner in steps. It is a principle that can now be found in any textbook on the subject.
Van Wees decided at an early age that he wanted to study physics. Chemistry was too broad, mathematics was too limited and biology was too messy, which left physics. ‘I’m a little lazy, but I’m also easily bored’, he explains. ‘So physics was the perfect choice.’
And yes, scientific research is a perfect choice for a lazy person, if that person happens to be named Van Wees. He only focuses on the research he likes and that he is good at. ‘We use a lot of different materials, but I don’t make those myself. That is not my expertise, so then I’m better off collaborating with people who are capable of that.’
These days he has focused on a fairly new field: spintronics. Spintronics focuses on the quantum mechanical characteristics of electrons: their spin. Each electron turns, or spins, around its own axis, and possesses a magnetic field. This spin can basically have two values: it can point up (a spin-up) or down (a spin-down). These tiny magnets can be used to store or send information. Every computer hard drive and every phone uses spintronics these days.
Spinning in graphene
Van Wees’ lab currently also holds the world record for the largest distance a spin current has travelled: 24 micrometres, or 24 thousandths of a milimeter. That may not sound very impressive, but is the largest distance a spin current has ever traveled. Moreover, it is far enough to be used in electronic applications. There is room for improvement however, because in theory, spin currents can travel almost a millimetre.
Van Wees has been working in this field since 2000. He makes all sorts of nanodevices from different materials to see how these spin currents behave. In this, he also works with graphene, a network of two-dimensional carbon that is only one atom wide. ‘Graphene can transport spin currents the farthest at room temperature, which makes it the best material for us’, says Van Wees. ‘Whenever possible, we work at room temperature, because that at least leaves some room for applications.’
The group made a very interesting discovery when they showed that it is possible to transfer information through an isolator. The electrical spin reaches the isolator, is transformed into spin current which reaches the others side and is transformed back into an electrical spin.
His focus on the practical use of his knowledge is also one of the reasons that Van Wees has been leading a work group within the EU Flagship Project Graphene since 2013, where he and other research groups and companies are seeking to identify applications for spintronics in graphene. But we should not expect the electrical currents in our phone to be replaced by spin currents within next few years. ‘I’m thinking of applications where you can combine materials with different properties in a smart way’, says Van Wees, ‘for instance a machine that can store information, make calculations, and communicate all at once. Right now, all these processes still take place in separate components, but by combining materials smartly, we might be able to do all that in one device.’
The physicist himself is modest about his achievements: ‘When you’re smarter than your colleagues in, say, China, you can achieve quite a few breakthroughs in this field without extensive experiments.’
I get to talk to ambitious people on a reasonably high level at the RUG, and I like that. And the students aren’t so bad either, in the end.
According to Van Wees, one his most cited articles is really quite trivial. ‘We proved that electron spins always choose the path of the least resistance. Water and electrical current do the same, so it’s really not that special.’
Van Wees has been working in Groningen for 24 years now and is head of the nanodevices group – part of the Zernike Institute for Advanced Materials. Together with his colleagues Caspar van der Wal and Tamalika Banerjee, he oversees a group of 40 people. It is a large group, and although he claims not to be a social animal by nature, Van Wees enjoys his job: ‘I get to talk to ambitious people on a reasonably high level at the RUG, and I like that. And the students aren’t so bad either, in the end.’
Part of his Spinoza Prize money will probably be spent on research into these combined devices. He does not yet know what he will be spending the rest of the 2.5 million on. ‘I do like that I’m free to spend the money as I wish. I’m going to take some time to think about what I might want to do, and I’ll just wait and see what comes along.’
In electronics, Moore’s Law is a well-known concept. In 1965, Gordon Moore, co-founder of computer chip manufacturer Intel, predicted that the number of transistors on integrated circuits would double every two years. The larger the number of transistors, the faster the chip works. Until now, chip manufacturers have been able to obey this law by making existing technologies smaller and smaller, but it would seem that the limit might soon be reached. A lot of people are looking to nanotechnology for a solution. Van Wees’ devices might just be the next step beyond Moore’s Law, but that time has not yet come. ‘We first have to understand everything on an atomic level’, says Van Wees. ‘If we succeed in that, we can work on scaling things back up again. And micro-electronics aren’t even our first goal; we first want to make multifunctional devices.’