Experiments in magnet lab reveal secrets of very promising semi conducter

Researchers at HFML-FELIX have - in collaboration with scientists from Groningen and Singapore - made some important discoveries on a new and very promising semi conductor.
Maarten Kwaaitaal
When you aim special lasers at materials, the light can excite atoms in a way that changes the characteristics of the whole material. And this effect can be very promising for the development of future electronic applications that need to be extremely fast.
Researchers at HFML-FELIX have now succeeded in changing the characteristics of barium titanate, a material that can be found in as many as 700 parts in the average phone.
Getting atoms to move is – in this case – not the easiest thing to do, physicist Maarten Kwaaitaal explains. ‘You can compare it to pushing someone on a swing, or swinging on rings yourself. If you push or swing too softly nothing much happens. If you repeat the movement too quickly, you won’t get into a swing either. But if you use the momentum right, and you use enough force at the right moment, then you can get a very strong movement.’
In the lab they have done something similar: push on the atoms in a specific material, using the extremely powerful FELIX lasers. This basically shakes up the atoms in the material, making it stretch, or expand.
When you look at the material right at the moment a laser beam hits it, you can see waves ripple from the centre towards the edges. ‘Like when you throw a rock into a pond. Those waves are temporary, but some of the changes in the material last.’
The ripples in the material are partly caused by heat, but also by other effects that are still unknown. This is what they are currently trying to solve. But finding out what exactly happens when the laser hits the material is not easy. You can look at it using a microscope that takes a lot of pictures very quickly. But the changes in the material happen in nanoseconds, and the current flashes can’t keep up. This is one of the things they are working on: light pulses that are as quick as these changes. This way it should be possible to reveal the secrets of the ripple and stretch effect even more.
Even though they do not yet understand the effect completely, what they have discovered so far has already proven to be very interesting. With this technique, they can make lasting changes in the material. In this case: switching the polarization of the material. You can think of this as a mini battery. One side of the material has a positive charge and the other side a negative charge. Changing the polarization is promising for applications that need to store and adjust data with great speed. Think of a computer bit that has to change from 1 to 0. You can make it switch using electric fields, but with light you would be able to do it many times faster.
Of course, you cannot put the super strong lasers from the lab into a phone or computer. One of the next steps is getting the material to change in reaction to weaker light as well. But first, it is important to fully understand the process. And they have now made some important steps towards this.
The most recent paper on these finds can be found on the Nature website:
This paper from earlier this year is also worth reading if you want to find out more:
Contact information:
maarten.kwaaitaal@ru.nl
Researchers at HFML-FELIX have - in collaboration with scientists from Groningen and Singapore - made some important discoveries on a new and very promising semi conductor.
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