Milorad Milošević#

BIOGRAPHICAL NOTE#

Dr. Milorad Milošević was born on June 30th, 1977 in Smederevo, Serbia (Yugoslavia at the time). Difficult living and unstable political situation never presented too much of a challenge for him – instead, he emerged as the best student in the history of his hometown, particularly talented for natural sciences (o.a. champion of Yugoslavia in Chemistry, and champion of Serbia in Mathematics). Subsequently, he graduated from the Faculty of Electrical Engineering in Belgrade, Serbia, with a degree in electronics. He then continued his education through a master study in micro- and optoelectronics in the Department of Physical Electronics. The M.Sc. thesis resulted from a combination of Dr. Milošević’s up-to-date acquired skills in electronics and semiconductor quantum microstructures, on the topic of Quantum Wire Lasers. In parallel, Dr. Milošević worked for 3 years as a technical assistant at the University of Physical Chemistry in Belgrade, where he was involved in experiments on Ar plasmas and fullerenes, and gained valuable experience in analytical and (in)organic chemistry. Such early interests in state-of-the-art physics and chemistry definitely helped his later demonstrated scientific maturity.

Dr. Milorad Milošević joined the Condensed Matter Theory group in the University of Antwerp in September 2000, as a doctorate student, after he was awarded a Dehousse scholarship. His research was mainly oriented towards mesoscopic superconductivity, a hot topic of the moment, previously experimentally established at the University of Leuven, Belgium (by Prof. Dr. Yvan Bruynseraede and Prof. Dr. Victor Moshchalkov), and at the University of Manchester (Prof. Dr. Andrey Geim). Dr. Milošević’s work on superconducting (S) samples combined with magnetic (M) elements, immediately sparked. The exciting new feature of S-M hybrids is the competition between ferromagnetism and superconductivity, representing two antitheses in condensed matter physics, which is of abiding interest in fundamental and applied materials science. Superconductivity and ferromagnetism, when brought together within a nanometer scale, create fascinating and not yet fully understood quantum ground state and kinetic properties. Dr. Milošević managed to make valuable theoretical predictions in the early stages of his career, which were rewarded by several invited talks in international scientific meetings all over the world. Moreover, Dr. Milošević received five international prizes for his presentations over the last several years.

After completion of his doctorate (with distinction), Dr. Milošević took the post-doc position in the same department, and was soon after upgraded to a Research Leader position. This recognition of his scientific achievements came after his invited posts as a Visiting Scholar to the University of Rio de Janeiro, Brazil, and the University of Notre Dame, USA. In 2007, Dr. Milošević visited Argonne National Laboratory, arguably the best lab in materials-science in the USA. There he worked with leading scientists such as the Nobel Laureate Prof. Dr. Alexei Abrikosov, Prof. Dr. W.-K. Kwok, Prof. Dr. A. Koshelev, and Prof. Dr. V. Vinokur, on vortex, charge, and spin manipulation in superconducting hybrids and their futuristic applications.

However, although quite successful as it is, Dr. Milošević took another step-forward in 2006 when he obtained a prestigious Marie-Curie fellowship to study superconductor-ferromagnet hybrids experimentally in the University of Bath, UK. His first experimental results (direct observation of vortex-antivortex pairs in superconductors) were published in Physical Review Letters. He further applied different scanning probe microscopies and transport measurements on high-temperature superconductors and Yttrium-Iron-Garnet magnetic films, both very relevant for potential applications. For this and earlier works, Dr. Milošević received the Prize of the Research Council of UA in 2007.
Upon return from UK, Dr. Milošević is now building an independent career at UA, in the NANO Center of Excellence http://www.nano.ua.ac.be. He is currently (co-)promoting two senior and two junior Ph.D. students, and has successfully supervised one Ph.D. and three M.Sc. theses in the past. Students under his guidance have published more than 20 articles in the last three years.

MAIN SCIENTIFIC ACHIEVEMENTS#

The major achievements of Dr. Milošević can be summarized in the following:

(i) Theoretical description of magnetic pinning of vortices in superconducting films (Phys. Rev. B 66, 174519 (2002); ibid. 68, 094510 (2003); ibid. 69, 104522 (2004)). Using magnetic particles, vortex lines in superconducting films can be pinned. Such nanoengineered pinning of flux lines prevents their motion and dissipation of energy, resulting in the enhancement of the critical current in the superconductor. This is of great practical importance, and Dr. Milošević contributed several key articles to understanding the origin and nature of the interaction of vortices with magnets as artificial pinning centers. There derived asymptotic formulae received great attention in the field.

(ii) Vortex-antivortex phenomena (Theory: Phys. Rev. Lett. 93, 267006 (2004), Phys. Rev. Lett. 94, 227001 (2005); Experiment: Phys. Rev. Lett. 99, 127001 (2007)). Although analogous to matter and antimatter in the universe, Dr. Milošević demonstrated theoretically that vortices and antivortices may coexist in superconducting films with ferromagnets on top due to the specific magnetic field profile acting on the superconductor. Moreover, when brought together, such vortex-antivortex molecules around each magnet can form a lattice analogous to ionic crystals with different geometries. These fascinating structures, disobeying the general rule of matter-antimatter annihilation, have subsequently been experimentally observed during the work of Dr. Milošević at the University of Bath, UK (see the vortex-antivortex molecule in the figure).

(iii) 3D submicron superconducting and ferromagnetic elements. Recent advances in nanofabrication and synthetic chemistry have lead to a dramatic growth in research activity in the area of magnetic nanostructures, with key applications in data storage, medical diagnosis and quantum information processing. Due to the particular strengths of the different approaches much of the work has focused either on lithographically patterned thin film (2D) mesostructures or nanoscale particles and clusters. In contrast, very little work has been attempted on 3D mesostructures with dimensions ~1m, whose sizes are comparable with the relevant characteristic physical lengthscales (e.g. ferromagnetic domain size or superconducting coherence length). In a remarkable recent paper Xiao et al. at Argonne National Lab have demonstrated that ‘architecture-tunable’ Pb and Co meso-structures can be grown by electrodeposition from lead nitrate or lead acetate solutions onto graphite substrates (see figure). Dr. Milošević investigated such submicron structures with a wide range of morphologies, both experimentally and theoretically, while developing state-of-the-art, world-unique numerical code for fully 3D calculations within stationary ant time-dependent Ginzburg-Landau theory, as well as Landau-Lifshitz-Gilbert magnetic simulations. Using those approaches, with no taken approximations, the superconducting/magnetic state of these elements was studied numerically exact, with emphasis on optimizing the critical properties, maximal field and current the element can sustain, and current-voltage response as a function of the chosen materials, their geometry, and direction of applied dc or ac drive with respect to the sample topology. The results on both superconducting and magnetic polyhedra have attracted immense attention in the scientific community.

(iv) Vortex logic elements (Appl. Phys. Lett. 91, 212501 (2007); Phys. Rev. Lett. 103, 217003 (2009); Appl. Phys. Lett. 96, 192501 (2010);). Another example of Dr. Milošević’s work towards applications is his proposal of Fluxonic Cellular Automata (FCA). He designed a nanoscale superconducting device, in which positions of vortices are manipulated by applied current, thus electronically. In such a way, controlled transitions between two energetically degenerate states can be achieved, which can be labeled as logic ‘0’ and ‘1’. When put together, logic cells interact via magnetic field, which enables the transfer of information, and Dr. Milošević demonstrated operation of a majority gate (the basis of all logic gates, see figure) using this principle. This work was not only published in Applied Physics Letters, but was also featured on the cover page of the November issue in 2007. Very recently, scientists in Japan realized experimentally the electronic manipulation of vortices in mesoscopic superconductors, a first step towards realization of FCA.