High performance computing of advanced magnetic structures designed for tomorrow’s memories and sensors
Financed by the Romanian National Authority for Scientific Research, CNCS – UEFISCDI, project number PN-II-RU-TE-2011-3-0211
In the last decade the magnetic devices industry – and in this project we are referring to both storage devices like hard-disk drives components or magnetic random access memories (MRAM) and to sensor applications – has suffered two major changes:
”Monte Carlo modeling of domain structures and switching properties in ferroelectric ceramics”, financed by the Romanian National Authority for Scientific Research, CNCS – UEFISCDI
Nr. contract: PD 160/2018
Code: PN-III-P1-1.1-PD-2016-1069
Project Director: Asist. univ. dr. Leontin PADURARIU
(Faculty of Physics, Alexandru Ioan Cuza University, Iași)
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Ferroelectrics are multifunctional materials with a large applicability in microelectronics. The main characteristic of ferroelectrics is that, below a critical temperature (Curie temperature), they present spontaneous polarization and domain structure. This feature represents the physical origin of all macroscopic properties of ferroelectrics: switching (memory), nonlinear dielectric properties, piezoelectric, pyroelectric and electrooptic properties. Experimentally, it was demonstrated that ferroelectric domain structures are affected by many factors as: electrical and mechanical boundary conditions, average size of grains and boundaries in ceramics, the concentration and nature of the dopants in solid solutions, microstructural particularities in composites etc. Therefore, new materials with improved functional properties will be able to be produced, only by understanding the way these factors influence the domain structures. This goal can be achieved only by a modeling/simulation approach. In the last years, an intense research was dedicated in developing theoretical models able to describe properties of ferroelectrics at limited length scales, but a real breakthrough in the field would be realized by integrating these approaches into a complex multiscale model. The major objective of the project is to develop an innovative multiscale Monte Carlo model integrating Landau-Ginzburg-Devonshire theory and Finite Element Method, aimed to provide a powerful tool for describing ferroelectric properties of polycrystalline ceramics under realistic electrical and mechanical boundary conditions. During the project, the Monte Carlo model will be used to describe different fundamental problems of ferroelectricity: grain size effects, compositional effects in chemically inhomogeneous systems and microstructural effects in composites.
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| Asist.dr. . Leontin PĂDURARIU | Project Leader |
| Prof. Univ. Dr. Habil. Cristian ENACHESCU | Mentor |
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The major objective of the project is to develop a complex Monte Carlo Method (based on Landau-Ginzburg-Devonshire theory and Finite Element Method) capable of describing domain structures and switching properties in ferroelectric ceramics in order to understand the role of geometrical, electrical and elastic parameters on their functional properties. The specific objectives are: (i) modeling of the ceramic effects in ferroelectric materials, (ii) investigation of the compositional effects in ferroelectric ceramics, (iii) study of the microstructural effects in ferroelectric-based composites.
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Expected results: Based on modeling approach, new methods of tailoring functional properties in ferroelectric ceramics by engineering local strains, charges and local electric field (material design) will be proposed. The deliverables of the project are:
- a model able to describe domain growth and local electric fields in ceramics;
- a model able to describe switching properties in ferroelectric ceramics with different grain sizes;
- a model capable to describe switching properties in ferroelectric based composites with different microstructural characteristics;
- scientific reports;
- ISI publications;
- oral presentations at international conferences.
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ISI publications
- N. Horchidan, L. Padurariu, C.E. Ciomaga, L. Curecheriu, M. Airimioaei, F. Doroftei, F. Tufescu, L. Mitoseriu, Room temperature phase superposition as origin of enhanced functional properties in BaTiO3 - based ceramics, J. Eur. Ceram. Soc.,40, 1258-168 (2020). Available online from 2019. Impact factor: 4.495, TOP I (accordingly to UEFISCDI classification). This work was realized in collaboration for experimental part with the UEFISCDI project PN-III-P4-ID-PCE-2016-0817. https://www.sciencedirect.com/science/article/pii/S0955221919308441.
- L. Padurariu, V.A. Lukacs, G. Stoian, N. Lupu, L. Curecheriu, Scale-Dependent Dielectric Properties in BaZr0.05Ti0.95O3 Ceramics, Materials, 13, 4386 (2020), Impact factor: 3.057, Yellow area (accordingly to UEFISCDI classification). This work is fully reported at this project.https://www.mdpi.com/1996-1944/13/19/4386
- L. Padurariu, C. Enachescu, L. Curecheriu, L. Mitoseriu, Why pyroelectric response is higher at Orthorhombic-Tetragonal than at Tetragonal-Cubic phase transformation in BaTiO3-based ceramics? Manuscript in prepartion. Expected year of publication: 2021. This work is realized in collaboration for experimental part with the UEFISCDI project PN-III-P1-1.1-TE-2019-1689.
Presentations at international conferences:
- L. Padurariu, I. Turcan, V.A. Lukacs, A. Cernescu, L. Curecheriu, C. Ciomaga, G. Stoian, N. Lupu, L. Mitoseriu, The Role of Composition on the Dielectric and Ferroelectric Properties of Ag-BaTiO3 Composites: Experiment and Modeling, poster presentation at the conference Joint ISAF-ICE-EMF-IWPM-PFM, organized in Lausanne, Switzerland, in the period 14-19 July 2019. This work was realized in collaboration with the UEFISCDI project PN-III-P4-ID-PCE-2016-0817. https://conf.papercept.net/conferences/conferences/ISAF19/program/ISAF19_ProgramAtAGlanceWeb.html
- L. Padurariu, C. Enachescu, L. Mitoseriu, Modeling of the Grain Size Effects in Nanostructured Ferroelectric Ceramics, oral presentation at the conference Processes In Isotopes And Molecules organized in Cluj-Napoca, Romania, in the period 25-27 September 2019. http://pim.itim-cj.ro/pages/programme.html
- L. Padurariu, C. Enachescu, L. Mitoseriu, Modeling of the Grain Size Effects in Nanostructured Ferroelectric Ceramics, oral presentation at the conference Asian Advanced Materials Congress, organized in Singapore in the period 31 October - 4 November 2019. https://www.advancedmaterialscongress.org/nov19/pages/program
- L. Padurariu, N. Horchidan, M. Airimioaei, L. Curecheriu, C. Ciomaga, L. Mitoseriu, Room temperature phase superposition of barium titanate- based ceramics: modeling and experimental validation, oral presentation at the conference Electroceramics XVII organized in Darmstadt, Germany, in the period 24-28 August 2020. https://www.electroceramics.org/en/electroceramics-xvii/welcome.html
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Reports:
2020 - Final report (in Romanian)
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A new generation of paradigms in the molecular magnetism and material sciences. The magnetic anisotropy in complex units, supramolecular systems and at nano-scale
Funded by Romanian CNCS as PCCE9/2010, implemented by six teams from Romanian Universities and Research Institutes.
The magnetic anisotropy in complex units, supramolecular systems and at nano-scale draws a new axis among top subjects of the molecular magnetism, illuminating key factors such as spin coupling, magnetic anisotropy, relaxation and tunneling of magnetization, that govern special properties, like the single molecule and single chain magnet behavior.
Cooperative switching in molecular materials induced by an elastic field produced by an ultrashort laser pulse – COOPSWITCH
Financed by the Romanian National Authority for Scientific Research, CNCS – UEFISCDI, project PN-III-71BM/2017
The research project described in the proposal will be conducted by investigators at the Excellence Center for Applied Research in Physics and Advanced Technologies (CARPATH) of the Faculty of Physics, “Alexandru Ioan Cuza” University (UAIC) from Iasi, Romania, and University of Rennes 1, France. This project will mix the expertise of the Collet group at IPR for photoinduced phase transition and ultrafast experimental studies and the expertise of the Enachescu group for modelling elastic coupling associated with these cooperative effects. These teams have complementary expertise: the group of University of Rennes 1 is one of the most important in the world with unique experimental facilities for the study of femtosecond phenomena in molecular materials, while the physicists at UAIC are internationally renowned for their models elaborated in order to characterize both spin crossover and magnetic materials and equally proposed new methods to analyze experimental data. The cooperation between the members of Rennes team and members of CARPATH started in 2012 and has been concretised up to now in a recent paper published in Nature Materials, at the heart of the present project.
Thanks to remarkable development of ultrafast techniques, operating on time scales faster than atomic motions or material reorganizations, new opportunities have emerged to impact the macroscopic state of a material, and thereby change its physical properties. Several experiments at the cutting edge of the laser and X-ray technologies have provided essential insights into real-time transformations of diverse materials, from the melting of charge and/or spin order in electron correlated systems to molecular switching in the solid state. Contrary to coherent optical phonons long under scrutiny, coherently propagating cell deformations over acoustic time-scale, have not benefited from the same surge of effort, in particular when the crystalline medium exerts positive feedback on the constituents. A severe limitation to photoinduced transformations triggered by a femtosecond laser pulse is their transient nature. A vast majority of reported experiments point to fast relaxation of excited electronic state and induced rearrangements of atoms inside unit cell, as factors prohibiting stabilisation. It is of paramount importance from the fundamental stand point, as well as for the control of non-volatile information, to explore whether induced crystal deformations have capacity to extend the lifetime of photoinduced states.
The goal of this project is to address the issue of the switching of materials by light pulse from the perspective of elastic cooperativity, notwithstanding its common perception related to electrons and optical phonons, we choose in this project to focus on spin-crossover systems where the phase transitions are driven by elastic interactions due to the swelling of photoswitched molecules.