Obituary of Bernard Coqblin (1940-2012)

Bernard Coqblin, well-known expert in the physics of rare earths and actinides, author of the pioneering book, The electronic structure of rare-earth metals and alloys: the magnetic heavy rare-earths (Academic Press, 1977), co-author of the “Coqblin-Schrieffer Hamiltonian”, and of several book chapters and review articles in anomalous rare-earths and strongly correlated electron systems (SCES), in addition to more than two hundred regular papers, passed away on 29 May 2012 at the age of 71.

After graduating from the Ecole Polytechnique in Paris, Bernard joined Professor Jacques Friedel’s group at Laboratoire de Physique des Solides, Université Paris-Sud, Orsay, as a researcher in Centre National de la Recherche Scientifique (CNRS). He obtained the degree of Docteur d’Etat in 1967. The subject of his thesis was the stability of localized magnetic moments in metals, and a description of the α-γ transition in Cerium. He then worked as a postdoctoral fellow with Professor J.R. Schrieffer at the University of Pennsylvania where he derived the “Coqblin-Schrieffer Hamiltonian” which allows a realistic description of the Kondo effect in rare earth ions like Ce or Yb. Until his death Bernard continued to actively pursue his research work at Laboratoire de Physique des Solides, Orsay, as a Directeur de Recherche Emérite of the CNRS.

His theoretical contributions cover many aspects of 4f and 5f materials, often focusing on the experimental results on magnetic and transport properties: Resistivity, magnetoresistivity, thermoelectric power, thermal conductivity, NMR and neutron spectra, etc. He was always in close contact with many experimental groups all over the world (Poland, Germany, Spain, US, Japan, Croatia, Brazil, France…) and regularly participated in the SCES conference almost every year, the last one in 2011. He organized several international conferences, in particular the SCES conference in Paris in 1998 and was one of the initiators of the series “Journées des Actinides”.

Bernard Coqblin was named Honorary Professor of Trzebiatowski Institute of the Polish Academy of Sciences, Wroclaw, in 2009. He also received the Doctor Honoris Causa from Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil in 2011. Bernard Coqblin has been the advisor of many students, and in particular students from South America (Brazil, Argentina and Venezuela) where he traveled often and had a number of collaborators.

Besides his numerous scientific contributions, Bernard was involved in many scientific committees in CNRS and Université Paris-Sud where he was very efficient, always trying to help young researchers. He will be remembered not only for his scientific contributions but also for his warm and gentle way of interacting with people and his constant disponibility for helping colleagues in difficult situations.