Robert Aart (Rob) de Groot studied chemistry in Groningen and had a short parallel career as high school (HBS) teacher. He continued in Groningen and completed his PhD thesis "On the electronic structure of some transition metal compounds" in 1976, under the supervision and guidance of Profs. Cor Haas and Wim Nieuwpoort. The computations for this work were mostly carried out at CECAM in Paris, where he stayed for a full year.
After a post-doctoral stay at the IBM Thomas J. Watson Research Center at Yorktown Heights, USA, Rob came to Nijmegen in 1978, where he joined the group BSB (Band Structure Calculations), headed by Prof. Fred Mueller. He stayed in Nijmegen until his retirement in 2014, in the FOM group Electronic Structure of Materials that he headed from 2001. In 1991 he became professor in chemical physics in Groningen.
Though in his thesis he included some experimental work, Rob preferred to do his experiments, as he called it, on the computer. Rob was a specialist in electronic structure calculations, that he applied to study a wealth of materials problems, ranging from transition metal compounds, liquid metals, cathode materials to polymers. His main research interest was magnetic materials, to understand and manipulate their properties, with important contributions in magneto-caloric materials, 2p-magnetism, catalysis, and, foremost, half-metals.
In 1983 Rob discovered a new class of materials, the so-called half-metals, that, depending on the spin-polarization of the charge carriers, either conducted like metals or blocked the current like insulators. This result, reported in a seminal paper on NiMnSb in Physical Review Letters, still receives over 200 citations per year. Rob soon realized the importance of these materials for the field that is currently called “spintronics”, but that did not yet exist at the time. It lead him to the idea for a “spin transistor” already in the 1980s. In later work he uncovered the various physical mechanisms behind the phenomenon of half-metals and diligently worked to optimize their properties for possible applications.
Rob trained and supported many PhD students who could always count on his commitment and hospitality in Nijmegen. Several of his former students have successfully pursuit academic careers and carry on his legacy. At his retirement, Rob was still full of ideas, but, unfortunately, personal circumstances prevented him from pursuing these further.
We all remember him as an original and respected colleague, whose intellectual legacy will live on.
