Ola Nilsen tells Journal of Materials Chemistry about his hot paper.

Could you briefly describe what you achieved in this article? 
The main achievement has been to produce thin films of materials in the range La_1-xCa_xMnO₃ that show colossal magnetoresistive properties by the atomic layer deposition (ALD) technique. The present work proves that the ALD technique is capable of producing multicomponent materials with complex stoichiometries in a fully controlled way. We have demonstrated that the ALD-window for a multicomponent system is not necessarily restricted to the common denominator of the ranges of the ALD-windows for deposition of the individual components, but can actually be extended in temperature. Deposition of such multicomponent materials has hitherto been somewhat hesitant in the ALD community due to a suspected decrease in the temperature range of the ALD-windows.

Could you explain the significance of your article to the non-specialist? 
Complex oxides of the perovskite type show a vast range of interesting properties, e.g., electric-, magnetic- and optical-properties, that open up for wide applications. However, due to their rather complex stoichiometries such oxides can not easily be deposited as thin films by any technique. We have now proven that it is possible to deposit such materials in a controlled way by means of the atomic layer deposition technique. We have selected La_1-xCa_xMnO₃ as demonstrator system since such materials have a technological interest owing to their colossal magnetoresistive properties. We expect that our findings will encourage other research groups to use the same method to deposit technologically interesting materials. The method has a number of obvious benefits, e.g., the deposited films are rather dense and uniform and achieved at relatively low temperatures.

What has motivated you to conduct this work?
There are several motivations for our endeavours. First, we have a long and strong tradition in our group at the University of Oslo with respect to synthesis of novel bulk oxides with intricate physical properties, as well their complex characterisation, along with theoretical studies of their electronic properties. Second, for utilizing such materials for, e.g., sensor applications one needs to have the required skills to deposit them as thin films, as well as to control their chemistry and microstructure. Third, these results fall naturally into our strategy towards an ultimate goal of building controlled nanostructured oxide materials in terms of multilayered structures yielding with novel functions.

Where do you see this work developing in the future?
We hope to see that more complex oxide materials with interesting properties beyond those of, e.g., high-k oxides, are deposited by the ALD technique. The technique is brilliant for deposition on substrates with complex geometries, which should lead to a number of applications.

Are there any particular challenges facing future research in this area?
We now control the ALD process for making well-defined complex oxides. A major challenge for our future research is to develop comprehensive skills that make us able to characterize and to understand intricate nanostructures of such complex oxides, with the aim to predict a priori the properties that may emerge in a given system, hence providing a route towards materials design.

Ola Nilsen was born in Norway in 1973. He received his Dr. Scienct. in 2003 from the University of Oslo under the supervision of Prof. Helmer  Fjellvåg, Prof. Arne Kjekshus and Prof. Sigrid Furuseth. His research interests relate to synthesis of complex oxides and organic-inorganic hybrid materials with the ALD technique, where he has been the first to demonstrate growth the latter group by the ALD technique. He has also interests in crystal growth and its implications in thin film properties.