Prof.dr. Thomas T.M. Palstra

Mission , Strategy and Accomplishments

Executive Summary

Thomas Palstra holds a chair in Solid State Chemistry and has a leading research group in electric conduction, magnetism, superconductivity and ferroelectrics. His present scientific interests include crystal structure-property relationships of transition metal oxides, organic conductors and organic-inorganic hybrid materials. He has coauthored approximately 190 manuscripts which were cited more than 12000 times, resulting in a Hirsch-index of 54. He was elected in 2010 member of  the Dutch Royal Academy of Sciences.

Prof. Palstra has fulfilled a number of management responsibilities including vice-dean and dean of the Faculty of Science and Engineering (2008-2009), and is presently director of the Zernike Institute for Advanced Materials. He was responsible for the RUG Sectorplan Physics and Chemistry (2009) and for the self-evaluation of the Zernike Institute (2010). The latter resulted in a no.1 position in the ranking of the six top-researchschools, ex aequo with NOVA, astronomy. During his tenure as director, the Zernike Institute ranked worldwide as no.9 in Materials Research Institutes according to the Times Higher Education index, straddled between Princeton University and MIT.

Research Mission of the Solid State Chemistry Laboratory

The aim of the current research program is to utilize displacive, spin-, charge and orbital degrees of freedom to control the electronic and physical properties of metals, inorganic materials and molecular organic compounds. The research takes place on the highest international level, and is competitive with that of the best universities worldwide. This research will train Ph.D. students and Post-docs to become leading researchers in industry or academia.

Research Program

We synthesize materials in bulk and thin film form, and study the relationship between the crystal structure and functional, electronic and physical properties. Theoretical insight is obtained through band structure calculations. Our unique capability is a variety of synthesis methods, both for bulk and thin film materials, a large range of temperature, pressure and magnetic fields over which both the crystal structure and the electronic properties can be studied. We have interest in highly correlated electron systems, in particular A: transition metal oxides,TMO, B: molecular organic conductors (C60 , pentacene and hybrid materials), and C: multiferroic materials.

Strategy

Transition metal oxides form a class of materials with unparalleled diversity in physical properties. They both serve as model compounds for fundamental research and also find practical use in various applications. After my arrival in 1996 in Groningen, we have augmented our expertise in physical characterization with synthesis and crystallography.The focus over the last years has been on understanding and controlling electronic properties using lattice, spin- and orbital degrees of freedom. The focus into the future will expand towards 1. exploiting new physical properties at lateral interfaces 2. utilizing this knowledge of competing electronic phases in device-like geometries.

Organic conductors are considered as viable alternative for low-cost electronics. Furthermore, molecular organic compounds exhibit physical properties which can be treated on the same footing as those of the TMO, including non-conventional superconductivity, strong electron-electron and electron-phonon interactions. The focus of our effort remains on fundamental processes contributing to the electronic mobility of systems, including the consequences of polymorphism, impurities, grain boundaries. This focus is expanded with investigations of device performance, thin film transistors, surface properties, development of new materials (co-crystals and hybrid organic/inorganic materials).

Multiferroic materials combine magnetic and electric order. For most materials these properties are mutually exclusive as they are based on either partially filled or formally empty d-orbitals. A small class of materials combines these orders. This makes it possible to control electric/magnetic properties by magnetic/electric fields, respectively. We study the nature of the magnetoelectric coupling by combing structural studies with electric response in magnetic fields.

Research Group

The group consists besides myself of Prof. B. Noheda, who joined the group in 2004 as Rosalind Franklin fellow and who was awarded a prestigious NWO-VIDI fellowship in 2004. The group is complemented by Prof. R. de Groot, who fills a professorship as ‘buitengewoon hoogleraar’ in Electronic Structure Calculations. In 2005 G. Blake was awarded also a NWO-VIDI fellowship. I supervise approximately 4 PhD students, and have been (co)promoter of 12 PhD students. The group has two technical associates, ing. J. Baas and Mr. H. Bruinenberg and a secretary, Mrs. H. van Mil. The activities can be found on this site.

Funding for the research is granted by Chemical Sciences CW, Physics FOM ,both part of NWO- the National Science Foundation, Economic Affairs EZ through NanoNed, European Community, the University of Groningen, and the Center of Excellence Program of the Zernike Institute.

Citation from the Self-Evaluation of Science and Technology RUG 1996-2004

“This excellent group, established in 1996, is focusing on the electronic properties and charge transport properties of a wide range of materials ranging from transition metal oxides to organic conductors with the view that these systems have common characteristics, in particular strong electron correlations. The group is internationally well recognized and is among the most active groups studying highly correlated systems. Particularly remarkable is the combination of chemistry and physics skills.”

Accomplishments

During my Ph.D. until 1986, I studied the magnetic and electronic transport properties in intermetallics. This research attracted considerable attention with my discovery of the URu2Si2, the first antiferromagnetic superconducting system. After a short diversion to methane chemistry, I resumed this kind of research at Bell Laboratories on the recently discovered high temperature superconductors. My discovery of flux motion put a firm basis for the technological relevance of these materials in high magnetic fields and large electrical currents. As permanent staff member, my research concentrated on transport properties of organics and oxides. Important was our discovery of C60 superconductivity, and contributions to Colossal MagnetoResistance. In Groningen (from 1996) my approach widened considerably: we started a coherent synthesis effort, including crystal growth, and make extensive use of X-ray and neutron scattering. This meant that the emphasis shifted from an itinerant description to a local perspective. The synthetic effort was expanded by thin film pulsed laser deposition by Prof. Noheda.

As is common for materials science, the research involves many aspects of physics, chemistry, and crystallography. Therefore, it is very important to have good connections to and extensively collaborate with people that use complementary techniques. Also, theoretical contributions are instrumental for progress and understanding.

University of Leiden 1981-1986 Ph.D.

For my Ph.D. degree I studied three separate intermetallic compounds. (La,Al)Fe13 is an unconventional iron-based magnet, with a transition from a ferromagnetic to antiferromagnetic state with large magnetoresistive effects. Small band gap uranium based intermetallics such as UNiSn resulted in small band gap correlated behavior, a field that recently has become very prominent. Finally, I studied heavy fermion systems based on the prototypical compound CeCu2Si2. We systematically replaced Cu with other 3d, 4d- and 5d-metals and Ce by U. This way we noted that strong correlations are located at the boundary between Pauli-pramagnetic and antiferromagnetic states. This way we discovered superconductivity in URu2Si2 near 1K, below an antiferromagnetic transition at 17.5K. Using specific heat experiments, we showed that the same electron system is responsible for the magnetic as the superconducting order.

Bell Laboratories 1987-1989 post-doc and 1989-1996 member of Technical Staff

As a post-doc I studied the then newly discovered high-temperature superconductors. I discovered that the origin of the broadening of the resistive transition in magnetic fields is related to flux motion. The small pinning energies are caused by the two dimensional nature of these superconductors. This results in a rapid suppression of the critical current in magnetic fields, and limits the application of these materials.

As staff member I chose to refocus on organic conduction and cluster materials. We studied intensely organic radical compounds as new possible superconductors. After the invention of Krätchmer to synthesize bulk quantities of C60, we discovered superconductivity induced by alkali doping. We studied many aspects of charge transport including pressure, magnetic fields, stoichiometry, and the first fabrication of C60 based transistors.

The cluster compounds we studied are unique in the sense that it was possible to change to valence state from neutral to +1, +2, and +3 by adding electron accepting groups in interstitial voids. This way we could change the electronic properties only by changing the valence state.

In the early nineties the cluster research changed into studying the emergent colossal magnetoresistance materials. We found that chemical pressure has profoundly different electronic effect on the magnetoresistance as hydrostatic pressure, originating from a different crystallographic response.

Vice Dean Faculty of Science and Engineering FSE (2008-2009)

My responsibilities covered, besides being member of the Faculty Board, the education programs of the entire faculty. The activities cover aspects ranging from outreach programs, curricular development and assessment to accreditation of the programs. FSE has three education institutes: Natural Science and Technology, Informatics and Cognition, Life Science, with each an Education Director and support staff as well as an Faculty Education Office (FOB). The Education Directors and Head FOB reported to me.

Outreach : The faculty has increased its enrolment from less than 500 in 2005 to approx. 750 students in 2008. The outreach programs take place under the umbrella of ScienceLinX and the RUG Discovery Truck. In 2009 sizable funding near 1.4ME has been acquired for these activities from ‘Platform Beta Techniek’ in the Sprint program. To increase the enrolment in Physics and Chemistry a proposal is formulated for the ‘Sectorplan Natuurkunde en Scheikunde’ including funding for outreach activities, curriculum development and new Chairs in specific areas.

Quality : The Faculty is developing a uniform Quality Assurance system in which new legal requirements are being adopted with clear uniform procedures and responsibilities. Students and staff actively contribute to a cycle of actions: Plan, Do, Act, Check. The Faculty Board has made the Basic Qualification Education (BKO) a mandatory part of curriculum development, and made staff available to assist with the engagement and professionalization of educators.

Programs : General procedures and guidelines within the faculty are made more uniform to offer a transparent structure for all students and staff members. Various bachelor and master programs request specific attention. The Education Research group has been restructured to optimize the education support for the staff as well as the education research effort. For Industrial Management and Engineering a new management structure and curriculum is being developed, to enable to channel this new education program to be embedded in research programs. The physics program has been analyzed and various aspects are detailed which need improvement. For Biomedical Technology new impetus from our faculty has been provided.

Excellence : In the Bachelor program the faculty participates in the Honours College, for which the FSE contribution of 25 ECTS has been proposed. The program intends to start in the year 2009/2010. The Masters program offers Topprograms for four research directions, for which a new uniform definition, selection procedure and funding was established.

International Relations : an exchange program has been granted by the EU for student and staff exchange between the European universities of Bochum, Heidelberg, Uppsala and he Japanese universities of Osaka, Kyoto and Sendai. This is sponsored by the EU and I was the European coordinator.

The faculty should engage in changes in which students are offered a broad range of programs with ample choices to suit their interest, and to prepare them for a career in science, industry or society. As society continues to offer a more global perspective, our programs should reflect this trend in enrollment, program and staff.