Erinevate adaptiivse käitumisega keeruliste süsteemide seas on esile kerkimas frustreeritud kvantmagnetid, kuna neis ennustatakse leiduvat aine uusi eksootilisi faase ja olekuid spinn vedelikust ja spinnjääst kuni topoloogiliste isolaatoriteni ja foononklaas elektrikristallideni. Need kollektiivsed olekud võivad osutuda võtmerollides olevateks tuleviku kvanttehnoloogiate arenemisel, olgu need siis innovatiivsete materjalide süntees energiapüüdmiseks ja salvestamiseks, kvant-põimumise põhine tehnoloogia või siis ülieffektiivne kvantarvutus. Uute looduslike materjalide otsene verifitseerimine on olemasolevas müras, komplekssetes ilmingutes ja lisandite poolt varjatuna äärmiselt väljakutsuv. Me pakume uute kvantmagnetite väljasõelumiseks välja uue unikaalse ja effektiivse meetodi, kus mikroskoopiline teooria on ühendatud moodsaima eksperimentaalse lähenemisega.
Among complex systems with emergent behaviors, frustrated quantum magnets are coming to the forefront, as they are predicted to exhibit novel exotic phases of matter ranging from spin liquids and spin ice to topological insulators and phonon-glass electron-crystals. These collective states might play a fundamental role in future and emerging quantum technologies such as the synthesis of innovative materials for energy harnessing and storage, entanglement-enhanced sensing, and highly efficient quantum computation. The exponentially growing complexity of the Hamiltonians used to describe such systems prevents their efficient analytical study and numerical simulation. Moreover, direct verification in natural materials, sizable noise level, ubiquitous defects and impurities and the limited degree of experimental control is extremely demanding. We propose the combination of unique and efficient experimental techniques with microscopic theory to verify some promising novel quantum magnets.
This project aimed at the continuation and extension of a research strategy developed by the PI in the previous years. While there is less conceptual breakthrough in the methodology, the innovation lies in the large variety of materials considered, and in the systematic use of electronic-structure calculations in conjunction with experimental measurements. Frustrated quantum magnets form a very special class of materials where the interesting low-energy properties are entirely determined by localized electron spins and how they interact with neighboring spins. This is a topic at the forefront of current research activities in condensed matter physics. We studied the magnetic properties of a number of low-dimensional frustrated magnets exemplified by the Sutherland-Shastry compound SrCu2(BO3)2 and BaCuSi2O6 known for the phenomenon of Bose condensation of magnons. We combined the experimental technique of nuclear magnetic resonance (NMR) and the computational method of density functional theory (DFT) to understand the magnetic behavior of these and other quantum magnets. Other materials we mentioned in the research proposal without a detailed description of the planned research resulted in a number of representatives of importand and interesting material classes: spin-Peierls inorganic oxides (TiPO4), frustrated spin-chain compounds (β-TeVO4), plaquette tetramer "cupula" systems (Ba(TiO)Cu4(PO4)4), clathrate-like ferromagnets (Eu7Cu44As23) etc. The main target of this project was increase of knowledge and fundamental understanding. By studying new materials, we aimed to contribute to the worldwide effort in exploring correlated quantum materials, in particular frustrated magnets. We tried to target interesting unsolved problems and discover new materials with original magnetic properties. The methodology was optimized to full use of the facilities available at the PI host institution and worldiwide (NHMFL, EMFL), and of publicly available cutting-edge computer codes.