COMAT: super-cool apparatus from Twente
In September 2012 Josée Kleibeuker will go to Cambridge University to continue her research. In Cambridge she will focus on improving the magnetic properties of materials by manipulating their structure and composition on the atomic level.
The MESA+ NanoLab is a room which – from a distance – looks like any other. However, appearances can be deceptive. This is the home of COMAT...
Above the glass door of room NL1037 we see a danger sign: ‘Beware laser’. Josée Kleibeuker, researcher in the Inorganic Materials Science group of professors Dave Blank and Guus Rijnders, opens the door with a key card. This is it then... the COMAT, the Complex Oxide MATerials system. Or to give it its Twente pet name: Kats Onmeunig Mooi App’raat oet Twente, or freely translated: ‘super-cool apparatus from Twente.’
The eight by eight metre room is virtually completely taken up by a sort of shiny metal octopus with four heads, seven long rods and numerous cables. There is a constant hum and whirring in the background. “That’s the cooling, the laser and the vacuum pumps,” says Josée Kleibeuker. Kleibeuker works with COMAT almost every day. She has now finished her doctoral thesis and obtained her doctorate cum laude in March, just one week before her contract finished. “I told my supervisors that I wanted to be finished within four years. And I did.” Kleibeuker started her research in 2008; the year in which COMAT had just reached completion. The apparatus cost € 2.5 million and is unequalled in Europe. Guest researchers visit MESA+ regularly to use this apparatus. Today a visitor from Italy and recently a scientist from Japan.
How does COMAT work, what kind of apparatus is it? Josée Kleibeuker, researcher at MESA+, explains: “This apparatus can make extremely thin layers of metal oxide and analyse them in detail. I can stack atoms on top of each other, layer by layer, and then examine what happens at the interfaces of those layers. Highly unexpected things can sometimes occur. For instance: I have placed one insulating material on top of another, and yet exactly at the interface of the two materials they apparently conduct electricity. There are different opinions as to how this is possible.” In other words, COMAT is able to stack atoms on top of each other layer by layer. To do this the researchers bombard a block of oxide crystal the size of a one euro coin with a laser. This laser bombardment heats a small piece of the block locally to approximately 40,000 degrees resulting in a small piece of the oxide being vaporised. The vapour then precipitates on the substrate, a tiny vitreous sheet the size of a little finger nail. In other words, the researchers have made a layer of oxide on the substrate, the thickness of a single atom.
If we wish to add another layer we shoot the laser at the block a second time. This vaporises more oxide that precipitates on top of the first layer. We can also use another block with a different oxide. In this way we are able to build up layers of different materials and produce completely new materials with astonishing properties. And we can also study those properties with COMAT.
COMAT consists of five ‘chambers’, shiny metal globes, each fitted with a small window resembling a porthole. Each chamber has a different function. Chambers 1 and 2 are used to make the layers. Chamber 3 is where the oxide blocks and newly produced materials are stored. Chamber 4 houses an Atomic Force Microscope that can explore the surface, atom by atom. And finally, chamber 5 houses a roentgen photo-emission spectroscope which is able to measure which atoms are on the surface and in what state.
All five COMAT chambers are interconnected. This means that the material need not be removed from the apparatus and this offers many advantages. There is a controlled vacuum area in COMAT and if the material is exposed to the atmosphere it will start to oxidise or can become contaminated. Moreover, it costs a great deal of time and energy to create a vacuum in the apparatus once it has been opened. The researchers can move the material from chamber to chamber through long rods with the assistance of magnets and pincers.
Fundamental and applied research
Josée Kleibeuker’s research into new materials is primarily fundamental by nature. But new materials also result in new applications. For instance, the researchers at MESA+ are engaged in work on piezo materials that can change shape accurately on command. Materials such as these are used for example in loudspeakers, inkjet printers and electron microscopes.
Name: Josée Kleibeuker (1984)
Position: Trainee research assistant (obtained her doctorate on 23 March 2012) with the Inorganic Materials Science group
Previously: Studied chemistry at the University of Groningen, preferably wants to carry out research abroad after obtaining her doctorate
MESA +... ‘has fantastic facilities. That’s one of the reasons why I wanted to do research here’