Dalibor Paar

Department of Physics, Faculty of Science, University of Zagreb

Dalibor Paar – biography and list of publications

List of publications

Dalibor Paar was born in 1969, Samobor, Croatia. He obtained his B.Sc. Physics in 1997, PhD. Physics in 2006 (Topic: "Microwave properties of YBa2Cu3Ox single crystals with different doping"). He was a PhD student  at the Physics Department of the Faculty of Science in Zagreb (1997-2008), visiting scientist at the Leibniz Institute for Solid State Physics in Dresden (2007-2008, short visits 2009-2012) and Assistant Professor at the Physics Department of the Faculty of Science in Zagreb (2009-today).
He started his career in the field of solid-state physics, he obtained his doctorate on the study of the microwave response of superconductors under the guidance of professor Antonije Dulčić. Later, he specialized in the field of solid-state NMR and participated in the establishment of the first such physics laboratory at the Department of Physics, Faculty of Science in Zagreb under the coordination of Professor Miroslav Požek. Subsequently, he started working on topics from environmental physics, more specifically nature protection and water management in Croatia.

Within the framework of scientific work, he is the initiator of several collaborations with experts from other institutes and faculties. In the field of solid-state physics, he initiated cooperation with the Leibniz Institute for the Solid State in Dresden and for the past ten years in the field of environmental physics with the Ruđer Bošković Institute in Zagreb, the physics departments on the University of Rijeka and University of Osijek, Croatian Waters and Croatian Geological Survey.
At the Department of Physics, he initiated new activities in the field of environmental physics. His key results in environmental science include the first insight into the geochemistry of sediments in Croatia and the perspectives of their study for the purpose of further paleoclimatic reconstructions, data collection and modeling of physical and hydrogeological processes in the karst relief and its subsoil, using the example of the study of the deep pits of the Velebit mountain using isotopic water tracing and other methods and monitoring of permanent ice in the mountains in the context of climate change. This research is currently being carried out through the ongoing scientific projects listed below.

At the IFW Dresden he contributed solid state research of new type of superconductors - pnictides discovered in 2008, based on metallic Fe-As planes. New superconductors have aroused great interest in the world scientific community, and they were among the first to be synthesized at IFW Dresden. With them, it is particularly interesting that the magnetic Fe2+ ion is directly responsible for the formation of superconducting condensate (the highest temperatures of the superconducting transition are currently 55K, these are the highest critical temperatures outside of cuprates). The NMR technique has proven to be important for the study of normal and superconducting properties of strongly correlated electronic systems.

Through FizKO EU project he worked on defining the standards of the environmental physicist profession on the national level. He developed cooperation with the system of nature protection and water management, applying physics in various environmental problems. As a representative of the Physics Department at the Faculty's Center for Climatic Research, he established interdisciplinary cooperation with experts in the fields of geophysics, geography and geology, and the implementation or preparation of projects is underway. In 2022, a project CARDIKARST under the coordination of professor Nenad Buzjak was started to study carbon dioxide in the environment with an emphasis on karst as a special relief. Previous research in which he is the main author included the study of drinking water in the karst underground and permafrost in in the context of climate change.

As part of his teaching activities at the faculty, he was mentor for more than 50 diploma (i.e., master) theses, through which methods and topics in physics teaching are often questioned and positive experiences and modern approaches to physics teaching are presented.  He improved the teaching in physics courses on the Department for Geology and environmental science students by creating manuals and new program content. With colleague prof. Poljak he is the initiator of two new university courses with the topic Popularization of science and scientific communication. As part of the EU FizKO project, he prepared the Department's strategy for improving teaching by introducing modern project-based physics teaching.

As part of the course Using computers in teaching since the beginning of the use of the British micro:bit microcomputer in GB, he introduced this device into the teaching of future physics and informatics teachers and encouraged the development of ideas on how to implement it in physics teaching. In addition to hardware, it participates in the initiative to introduce advanced methods in physics teaching, such as augmented reality. In the future, he intends to direct part of his scientific activity towards the improvement of physics teaching by introducing modern methods and placing the physics experiment at the center of the teaching process. He is also active in the introduction of physics content into the field teaching of schools, which is demonstrated by a series of science popularization projects that connect physical topics to real life and global problems of today in an interesting and motivating way for children. In cooperation with several kindergartens, he is working on the development of an early science education program, where children encounter the current topics of today's science and technology.

In the next 5 years, the applicant has the following research and activity plan:
•    Application of scientific research projects in the field of environmental physics and the application of experimental methods of solid-state physics on environmental samples. Cooperation with physicists from outside the Department who deal with this topic (Rijeka, Osijek) and other experts (IRB, Geography Department, Geology Department, Geophysics Department, Croatian Geological Survey). Interdisciplinary cooperation with colleagues from other departments.
•    Continuation of science popularization activities in cooperation with kindergartens, schools, museums, presentation centers and other institutions. The main goal is to arouse interest in physics and other STEM fields from an early age. Cooperation at the level of all departments on the popularization of science and mathematics through an open day and other popularization activities.
•    Further development of popularization activities at the Department through new courses in science popularization and scientific communication. Improvement of teaching at the Department, especially for educational physics study with an emphasis on experiments as a central part of physics teaching. Research on the effects of the introduction of modern methods in physics teaching. Research into the application of new ideas and equipment in the teaching of physics, especially within the framework of graduate theses (microcomputers, new concepts for performing physical experiments). 

Brief description of scientific and professional activities

The contribution to the research of several topics in the field of solid state physics and environmental physics is presented.

1. Investigations of non-resonant microwave response of superconducting samples
In the period until 2007, he participated in the experimental research of the Laboratory for High-Frequency Measurements of the Physics Department under the guidance of professor Antonije Dulčić and professor Miroslav Požek, which was based on the study of the non-resonant microwave response of superconducting samples as a function of temperature (5-200 K) and external magnetic field (0-16 T). The dynamics of weak bonds between superconducting grains in polycrystalline samples in strong magnetic fields, as well as in single crystals and thin films in which the superconducting sample is in a mixed state, were studied. Superconducting parameters such as the upper critical field, the coherence length and the release frequency of the magnetic vortices were determined using the theoretical models. Temperature and magnetic dependence of microwave absorption in ceramic and powder samples of superconducting hybrid ruthenocuprates RuSr2EuCu2O8 and RuSr2GdCu2O8 were studied. For the purposes of measurement, an experimental method was additionally developed for the precise determination of the Q-factor and frequency of the resonant microwave cavity as a function of temperature and external magnetic field. The coexistence of superconductivity and magnetic ordering can be described by unbonded RuO2 and CuO2 planes. RuO2 planes are conductive at all temperatures, even below the critical temperature when a superconducting arrangement occurs in CuO2 planes. The temperature and magnetic dependences of YBCO single crystals were also studied. The experimental method was further upgraded with the possibility of simultaneous measurement in several resonant modes (9.33 GHz – 17.48 GHz), which enables the analysis of anisotropic properties of superconductors. In contrast to the optimally doped sample, the surface resistance of the underdoped sample along the c-axis in the normal state has semiconducting behavior and at the same time has metallic behavior in the ab-plane. The temperature dependence of the complex conductivity in the ab-plane and along the c-axis of the sample was determined, and from this the London penetration depths in the ab-plane and along the c-axis were calculated. An analysis of the magnetic dependencies of the surface impedance was made using the effective conductivity model, which enables the determination of the upper critical field and the dynamics of vortices in the optimally doped and underdoped sample. In both samples in the orientation in which the external magnetic field is parallel to the c-axis of the sample, magnetic dependences of the surface resistance with an inflection point were observed, which moves towards higher fields as the temperature decreases. A possible explanation is given as a sign of the phase transition of the mixed state from the glassy to the liquid phase of the vortices.

2. NMR/NQR research of superconductors
As part of his post-doctoral and subsequent stays at the Leibnitz Institute for the Solid State in Dresden and as part of the newly established laboratory for solid state NMR at the Physics Department of the Faculty of Science (head: Prof. M. Požek). D. Paar worked on NMR/NQR research of materials, especially new superconductors. He established cooperation with the NMR group of Dr. H.-J. Grafe at IFW Dresden. Nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) are one of the leading methods for studying the structure and dynamic properties of materials. The NMR technique allows not only insight into the local electronic and magnetic structure of these compounds, but also provides information on electronic spin dynamics and magnetization. Therefore, the nuclei that are bound to the electron spin system can be observed in different ways. With these investigations, it is possible to observe local inhomogeneities in spin and charge density, and previous studies indicate that such spatially inhomogeneous charge distributions play an important role in the mechanism of high-temperature superconductors. As part of the post-doctoral project "Research of high-temperature superconductors with nuclear magnetic resonance", NMR and NQR measurements of various superconductors were performed, with special emphasis on ruthenocuprates and YBCO single crystals. Quasiparticle excitations and vortex cores in the mixed state of superconductors were studied by NMR spin-lattice T1 relaxation time measurements. The dynamics and vibrations of the vortices were studied by T2 spin-spin relaxation measurements. NQR measurements provide information on inhomogeneities and charge fluctuations in the CuO2 planes. A new group of superconductors - pnictides discovered in 2008, based on metallic Fe-As planes was investigated. New superconductors have aroused great interest in the world scientific community, and they were among the first to be synthesized at IFW Dresden. With them, it is particularly interesting that the magnetic Fe2+ ion is directly responsible for the formation of superconducting condensate (the highest temperatures of the superconducting transition are currently 55K, these are the highest critical temperatures outside of cuprates). The NMR technique has proven to be important for the study of normal and superconducting properties of strongly correlated electronic systems. NMR studies of the 75As core in the compound LaO0.9F0.1FeAs revealed a strong temperature dependence of the spin-lattice relaxation time and a Korringa-shaped dependence. In the superconducting state, the measurement results indicated spin-singlet pairing, and the strong anisotropy in the spin-lattice relaxation time is a possible consequence of the contribution of superconducting vortices.

3.    Research in the field of Environmental physics

These researches represent an extension of experimental physics topics at the Department. Entering this topic opens up opportunities to apply the knowledge and equipment we have at the Department for the needs of various stakeholders, such as nature protection systems, water management and the energy sector. A broader approach to environmental issues was encouraged at the faculty level by the establishment of the Center for Climatological Research. Research activities related to environmental physics were recognized as an important part of these activities. In the field of environmental physics, he initiated research within the topic "Physical, chemical, geomorphological, hydrological and microbiological research of processes between the surface and underground of the Dinaric Karst". During the application of the CeNIKS project to the FO, thanks to this cooperation, the project was supported by stakeholders from the nature protection system, and the potential of the equipment that was procured for the analysis of environmental samples was recognized. The first results were published in Q1 and Q2 journals, and s new scientific project CARDIKARST coordinated by professor Nenad Buzjak started in 2022. The results of preliminary research show further perspectives in the direction of paleoclimatic and paleoenvironmental reconstructions. It is expected that the composition of elements and mineralogy of sediments from different places in the Croatian karst reflect different climatic, geological, geomorphological and hydrological characteristics of the karst areas.
Applied physical research in the environment represents a great potential, both because of the need for such research for the purpose of managing and protecting natural resources and because of the fundamental issues of changes in the environment. As EU funding sources are significantly focused on environmental and climate change issues, the Croatian karst represents an ideal training ground where these issues can be considered with the application of a range of research techniques successfully used by Croatian physicists. Karst is a complex system in which a number of processes take place in the interaction of the surface and the subsoil with natural and possible anthropogenic influences. Caves are natural laboratories where it is possible to clearly define and study these processes, associate them with physical variables and observe their space-time dynamics. The role of physicists in this consideration is to distinguish the key variables and apply physical models of speleogenesis and morphogenesis, heat flow and underground microclimate. These studies should be accompanied by appropriate geological, geomorphological and hydrographic research, which contributes to the interpretation of the observed processes. The importance of karst in this consideration has become globally more important in the last decade, since cave sediments contain unique archives of paleo- and recent climate changes. They have long formation intervals and a wide geographical distribution, and they can be conserved underground without significant external influences. The key information in them is found in multiple markers (proxy records) which are directly and indirectly related to climatic, geomorphological and hydrogeological conditions. It is especially important that cave sediments, in addition to well-defined formation conditions related to the understanding of speleogenesis and the influence of climatic conditions on the surface, have extremely good preservation in relation to denudation and bioturbation after deposition. Research includes the study of geochemistry and mineralogy of slag and other sediments, physical research with an emphasis on deep pits (microclimate, radon, CO2), hydrogeological research (origin, quality, water dynamics, isotopic analyses), permanent ice in pits and climate change.

Leading or participating in scientific and professional projects
1.    Collaborator on the project Dynamics and distribution of CO2 in karst vadose and epiphreatic zone (CARDIKARST) (Leader: Nenad Buzjak). Duration: 2022 to 2025. Amount of financing: EUR 127 897
2.    Collaborator on the project Development of physics studies with the application of the Croatian qualification framework (https://pdb.irb.hr:8443/project/irb:006276) (Leader: Mladen Petravić). Duration: 2019 to 2022; Financing amount: EUR 529 784
3.    Collaborator on the project Implementation and improvement of professional practice at PMF (https://pdb.irb.hr:8443/project/irb:005990) (Leader: Sofia Ana Blažević). Duration: 2020 to 2022; Financing amount: EUR 529 892
4.    Collaborator on the project Microclimate of speleological objects in Croatia (https://pdb.irb.hr:8443/project/irb:008005) (Leader: Nenad Buzjak). Duration: 2022 to 2025;
5.    Collaborator on the project Microclimatic research of Samograd cave and Medina cave (https://pdb.irb.hr:8443/project/irb:008007) (Leader: Nenad Buzjak). Duration: 2022 to 2023;
6.    Collaborator on the project Microclimatic research of the Samograd cave (https://pdb.irb.hr:8443/project/irb:007685) (Leader: Nenad Buzjak).
7.    Collaborator on the project Local Probe and Mesoscopic Dynamics in New Phases of Highly Correlated Electronic Systems (https://pdb.irb.hr:8443/project/irb:003238) (Leader: Miroslav Požek). Duration: 2014 to 2018; Financing amount: EUR 125 427
8.    Cooperation with the real sector: Coordinator of the scientific-research project "Explorations of deep pits of the Northern Velebit National Park" financed by the Fund for Environmental Protection and Energy Efficiency and the Northern Velebit National Park (2010-2022)
9.    Leader (PI) of the project "Water quality in the deep karst of Velebit" financed by Croatian Waters (2009-2019)
10.    Leader (PI) of the bilateral project Physical research of active and paleoenvironmental processes in Dinaric karst pits (https://pdb.irb.hr:8443/project/irb:005748). Duration: 2014 to 2015;
11.    Collaborator on the project Strengthening the SOLid state research capacities in Zagreb by the introduction of the Nuclear Magnetic Resonance method (https://pdb.irb.hr:8443/project/irb:005787) (Leader: Miroslav Požek). Duration: 2009 to 2012; Amount of financing: EUR 946 380
12.    Leader (PI) of the research project Investigation of high-temperature superconductors by nuclear magnetic resonance (https://pdb.irb.hr:8443/project/irb:000256). Duration: 2008 to 2009; Financing amount: EUR 7 339
13.    Collaborator on the project "Microwave research of new materials", HRZZ, 2007-2014. (Leaders: Antonije Dulčić, Miroslav Požek)

Member of the organizational or program committee of scientific and professional meetings
1.    17th Castle Meeting - New Trends on Paleo, Rock and Environmental Magnetism, Trakošćan, Aug 28 – Sep 3 2022.
2.    International Symposium "Geodiversity and Geoheritage - Status and Perspectives", Perušić, October 7-9, 2022.
3.    Solid-State Science & Research, Zagreb, June 10-11 2021.
4.    Solid-State Science & Research, Zagreb, June 27-29 2019.
5.    Scientific expert meeting "From research to good management of the Northern Velebit National Park". Krasno, 24-25. May 2017
6.    International Scientific and Expert Meeting "Geodiversity, Geoheritage and Geotourism in Karst Areas", Perušić, 18-19 February 2017
7.    Scientific-expert meeting Special values of deep karst, National Park Sjeverni Velebit, Krasno, April 21 - 22, 2012.
8.    Recent advances in broad-band solid-state NMR of correlated electronic systems, 4-9 September 2011, Trogir, Croatia
9.    Professional seminar on speleological cadastre, Perušić, 29-30. January 2011
10.    Recent advances in broad-band solid-state NMR of correlated electronic systems 5-10 September 2010, Trogir, Croatia.
11.    Professional seminar on the protection of caves and underground fauna, Ogulin, 30-31. January 2010
12.    Professional seminar on the creation and evaluation of a cave maps, Samobor, February 21, 2009.
13.    6th Scientific Meeting of Croatian Physical Society, Primošten, October 8 - 11, 2009.

Educational activities

Innovation of teaching content and publication of manuals
He improved the teaching of physics for students of the Department of Geology, Biology and Geography within the corresponding physics courses. He prepared the manual Physics for geosciences and environmental sciences. He also improved the teaching with field tours of the laboratories at the Department of Physics, the Ruđer Bošković Institute and the Institute of Physics, which aroused the interest of students in the interdisciplinary application of physics.
He improved the teaching in the Department by introducing modern content in the course Computer use in teaching. In addition to the Python programming language, he introduced practical work on British micro:bit devices that represent the front of modern education in Europe. The materials created within the course contribute to the modernization of physics and informatics teaching in schools and are available to all teachers in Croatia https://www.pmf.unizg.hr/phy/RUNA
Through a series of graduate theses under the mentorship of applicants, new educational content focused on using experiments in physics teaching and problem-oriented teaching was developed. In the framework of the EU project Development of physics studies with the application of the Croatian qualification framework (2019-2022), he coordinated the creation of guidelines for the introduction of project-based teaching in physics studies.

New course, new experimental or practical methods
Within the framework of the EU project FizKO, the applicant prepared a FO strategy for the introduction of project teaching, which was presented at the FO Council in December 2021.
The applicant is in cooperation with associate professor Nikola Poljak proposed 2 new courses:
• Popularization of science and scientific communication (research physics study)
• Popularization of science and scientific communication (educational physics studies)
The courses have been accepted by the Department of Physics, Faculty of Science, Zagreb in 2022.
Scientific and professional activities in the field of science popularization and scientific communication
Since 2018, the applicant has been working on the development of science popularization methods and their implementation from kindergarten to college. One of the results of these activities is the author's book - STEM in non-formal education for occupations of the 21st century (Paar et al. 2022).

Teaching activity 2017-2022 (last 5 years)
Course    Role    Period    ECTS    Teaching load
Physics 1 (171101)    Course instructor    2017-2022    5    Winter 2+0+2
Physics 2 (171109)    Course instructor    2017-2022    5    Summer 2+0+2
Physics (37632)    Course instructor    2018-2022    4    Summer 2+1+0
Physics (36208)    Course instructor    2017-2022    6    Summer 3+2+0
Use of Computers in Teaching (50846, 50851)    Course instructor    2017-2022    5    Summer 1+3+0
Energy and ecology (40727)    Course instructor    2017-2019    3    Summer 2+0+1

Teaching activity 1997-2017
Course    Role    Period    Teaching load
Physics 1 (171101)    Course instructor    2015-2017    Winter 2+0+2
Physics 2 (171109)    Course instructor    2015-2017    Summer 2+0+2
Physics (37632)    Course instructor    2018-2017    Summer 2+1+0
Physics (36208)    Course instructor    2015-2017    Summer 3+2+0
Physics 1 i 2
(36179, 37584)    Course instructor    2008-2014    Winter 2+2
Summer 2+2
Physics (36208)    Course instructor    2012-2014    Summer 3+2
Use of Computers in Teaching (50846, 50851)    Course instructor    2009-2017    Summer  1+3
Physics (35780)    Course instructor    2009-2012    Summer 2+2
Physics 1 i 2
(31418, 31419)    Course instructor    2008-2009    Winter 2+2
Summer 3+1
Basics of Physics
1, 2, 3 i 4.    Assistant    1997-2007    Winter 0+4
Summer 0+4
Use of Computers in Teaching    Lecturer    2006-2007    Summer  1+3
Multimedia Presentations    Lecturer    2005-2007    Summer  1+3

Other professional and institutional activities
2021 - 2022. Representative of the Physics Department at the Center for Climatological Research of the Faculty of Science, Zagreb
2013 - 2022 Representative of the Physics Department for e-learning at the University of Zagreb
2020 – 2022 Coordinator of the Physics Department in the Merlin e-learning system
2021 - 2022 Coordinator of the Open day of the Physics Department - Physics today
2022 - Coordinator of the registration of the Collection of studies and demonstration experiments of the Physics Department as a cultural asset of the Republic of Croatia
1999 - 2022. Editor of the website of the Physics Department
2018 - 2019. Assistant to the head for monitoring the work of the Department of Physics computer system
1999 - 2002. Creation of the lecture schedule of the Physics Department

Popularization of Science

Since 2018, the candidate has been actively working in the field of science popularization and is the initiator and manager of a series of projects in Croatia that work from an early age to popularize physics and STEM fields with the aim of more children deciding on the direction of STEM professions, thereby increasing interest for physics studies. Popularization activities are connected with activities at Department of Physics, such as the open day - Physics Today, and activities related to the Collection Physics Experiments at Department of Physics.
Science popularization projects
2018-2022. Coordinator of the science popularization project "Scientific (STEM/STEaM) education from an early age - towards modern education for professions and citizens of the 21st century", financed by the Ministry of Science and Education, hfd-steam.eu.
2018-2022. Coordinator of the science popularization project "Field teaching of the 21st century in Samobor" co-financed by the City of Samobor and the Ministry of Science and Education
2019-2022. Coordinator of the science popularization project "Explorers of Velebit Mt - early scientific (STEM) education for 21st century occupations" in cooperation with the Northern Velebit National Park with funding from the Ministry of Science and Education.
2021-2022. Coordinator of the Contemporary Science in Samobor Museum project financed by the City of Samobor, Zagreb County and the Ministry of Culture
2018-2019. Coordinator of the "Physics in Kindergarten" program in cooperation with Izvor Kindergarten, Samobor, Trešnjevka Kindergarten, Zagreb and Tratinčica Kindergarten, Zagreb.
2019-2021. Coordinator of project activities of the project "STEaM Lika - through education to sustainable development", financed by Switzerland within the Swiss-Croatian cooperation program, steam-lika.eu
2019-2022. Head of the "Samobor Summer School of Science and Technology", a program intended for elementary school students
2019-2022. Coordinator of the PMF-Lumen project, pmf-lumen.eu
2018. Coordinator of the popular science event "Explorers of the 21st Century" for about a thousand students of Ogulin elementary schools, held on November 23, 2018 in Ogulin.
2019 Coordinator of the popular science event "Little researchers: Earth needs our help. Let's explore and protect it!" for 200 elementary school students in Samobor, held on May 5, 2019, in the Prica Small Gallery in Samobor.
2019 Coordinator of the presentation of the STEM education program MOHOROVIČIĆ with interactive physics experiments. Samobor Museum, 23/07/2019.