Prof. dr hab. Roman Micnas

Prof. Roman Micnas, one of the most distinguished scholars of our University and a well recognized international scientific authority, died on January 13th, 2022. He was full member of the Polish Academy of Sciences, a member of its governing council and held the position of the Dean of Division III: Mathematics, Physics, Chemistry and Earth Sciences.

Professor Roman Micnas was born on November 4th, 1947, in Nowice, Poland. He graduated from the Faculty of Mathematics, Physics and Chemistry, Adam Mickiewicz University in 1970. In 1978 he defended his PhD thesis entitled “The Influence of Crystal Fields on Collective Magnetic Excitations in Systems of Rare Earth Ions“, under the supervision of Prof. Leon Kowalewski. This work, in the opinion of the thesis committee, contained original scientific achievements at the level of habilitation theses and was awarded an individual prize by the Minister of Science, Higher Education and Technology.

At that time his scientific interests were focused on the study of phase transitions and critical phenomena in electron and spin systems, the theory of electron systems with strong electron correlations and the theory of superconductivity. He developed functional integration methods to study classical and quantum spin models. He used the Mori-Zwanzig technique in generalized Green’s function theory to study systems with multilevel energy structure in anisotropic magnets, systems with quadrupole couplings, the Hubbard model, as well as to analyze impurity conduction in semiconductors. He developed the theory of so-called quantum critical phenomena in the presence of random magnetic fields using the renormalization group method and obtained a number of interesting results, e.g., novel dimensional dependence of critical exponents in quantum spin models, band magnets and quantum ferroelectrics.

In his subsequent publications, R. Micnas presented the results of studies of the influence of structural disorder on electron ordering and superconductivity in narrow band systems. In these works, phase diagrams of the Hubbard model with structural disorder were developed and the influence of random magnetic fields on first order phase transitions and multi-critical phenomena in equivalent pseudospin models was investigated.

The results of this research constituted the basis of his habilitation thesis entitled: “Study of phase transitions and critical phenomena of electron and spin systems incorporating quantum and disorder effects“, which he submitted in 1986. R. Micnas received his habilitation degree (dr hab.) in 1988. The scientific achievements presented in the habilitation dissertation were deemed to be of such a rank as to subsequently justify the commencement of proceedings for the conferment of the title of Professor. And indeed, in May 1990 he was awarded the scientific title of Professor of the Physical Sciences. At that time he took up the position of Associate Professor (Professor Extraordinarius), and in 1996 that of Full Professor (Professor Ordinarius) at our University.

In the years 1980 -1987, R. Micnas and S. Robaszkiewicz in collaboration with K.A. Chao (University of Linköping, Sweden) and J. Ranninger (CNRS – Grenoble, France) developed the foundations of the theory of superconductivity and charge ordering in narrow band systems with local attractive interactions, including the model of superconductivity of local pairs and the boson-fermion model. These published works were pioneering in many aspects. The theory of coexisting local pairs (bipolarons) and itinerant electrons, developed by R. Micnas, J. Ranninger and S. Robaszkiewicz, showed the possibility of the occurrence of a completely new kind of superconductivity, viz. of the charge exchange type in materials in which local electron pairing occurs. This work was actually submitted for publication before the experimental discovery of high temperature superconductivity in 1986. Since then, Roman Micnas and his collaborators continued very intensive research on various mechanisms of superconductivity and the resulting published papers gained wide international resonance.

Roman Micnas together with J. Ranninger and S. Robaszkiewicz, were invited by the editors of the renowned American scientific journal Review of Modern Physics to write an an extensive review article summarizing the current state of the theory of electron systems with local pairing interactions, which was published in 1990. This work has been cited more than 1400 times and is one of the most cited scientific articles in the area of physics in the country.

Roman Micnas and Stanislaw Robaszkiewicz received the Maria Sklodowska-Curie Scientific Award of the Polish Academy of Sciences in 1989 for their work on the theory of superconducting systems with local electron pairing.

At the Faculty of Physics, Adam Mickiewicz University, Prof. R. Micnas headed the Doctoral Studies Programme from 1991 to 2002 and was Vice-Dean for Scientific Affairs during the 1999-2002 term. In the subsequent terms from 2005 to 2012, he was a member of the Senate of the University, where he was part of the Senate Committee for Development. From 1998 until his retirement in 2018 he was the Head of the Department of Solid State Theory (which has since been transformed into the Department of Condensed Matter Theory). He took over this function from Prof. Leon Kowalewski.

During his scientific career, Prof. Micnas published over 140 scientific articles mainly in foreign scientific journals and presented over 50 communications at international and national scientific conferences. These works are widely recognized around the world and so far have been cited about 3300 times by other authors. He presented the results of his scientific achievements at numerous international and national conferences, international schools of theoretical physics and symposia on high temperature superconductivity, magnetism, many-body systems physics and electron correlations. He had a total of over 60 invited lectures at, among others, the International Conference on Magnetism in Paris, conferences in Les Houches and (thrice) at the E. Majorana Center (Erice, Sicily), in Switzerland, France, the Netherlands, USA, China, the NATO Conference in Greece as well as in Poland – e.g. a plenary lecture at the Jubilee XXXIII Congress of Polish Physicists. In addition, he presented the results of his research at over 40 seminars and departmental colloquia at leading scientific institutions in Europe and the USA. He gave 5 series of lectures abroad, in Sweden (University of Linköping, 1978), Brazil (1980) and in France (Grenoble, 1987).

In connection with his extensive scientific cooperation with leading scientists from all over the world conducting research in the broad field of condensed matter physics, especially superconductivity, phase transitions and critical phenomena, and electron correlation theory, he was invited as Visiting Professor to 15 scientific centres in Sweden, Brazil, France, Italy, Germany, Switzerland and the USA.

Prof. Roman Micnas co-organised 35 international and national scientific conferences and schools of theoretical physics. Since 1993 he chaired or co-chaired the European Conference “Physics of Magnetism” held every three years in Poznań, which is one of the largest conferences of its kind in Poland.

He received many awards for his achievements. In the years 2003-2006 he was a beneficiary of the Professorial Grant programme “Master”of the Foundation for Polish Science. Six candidates obtained their Ph. D. degrees under the supervision of Prof. Micnas. He directed 10 research grants. Prof. Micnas conducted research centered around the most important and frontier topics of condensed matter physics. Apart from the earlier mentioned directions, he also conducted research on models of many body physics describing ultracold quantum, fermionic or bosonic atomic gases trapped in optical lattices.

Professor Roman Micnas was one of the most outstanding scholars of our University. A person endowed with extraordinary talent and enormous diligence, he quickly became an internationally recognised scientific authority with extensive and profound scientific knowledge in theoretical condensed phase physics, the theory of many-body systems and statistical physics. His scientific output will remain for years in the educational canon of every scientist conducting research in these fields.