\u2022<\/span><\/span>\u00a0 Streda <\/span>04.03.2026 <\/span><\/span>o 11:00 hod. <\/span>\u00a0Budova PROMATECH (m.\u010d. 108), Watsonova 47A, Ko\u0161ice<\/strong><\/p>\n <\/p>\n Siln\u00e9 korel\u00e1cie a frustr\u00e1cia:<\/strong><\/a> <\/p>\n RNDr. \u013dubom\u00edra Regeciov\u00e1, PhD.<\/strong><\/p>\n Oddelenie teoretickej fyziky \u00daEF SAV, v. v. i. Anot\u00e1cia:<\/strong><\/p>\n Silne korelovan\u00e9 syst\u00e9my a frustr\u00e1cia predstavuj\u00fa prirodzen\u00e9 prostredie pre vznik netrivi\u00e1lnych magnetick\u00fdch a termodynamick\u00fdch javov. V na\u0161ich ned\u00e1vnych pr\u00e1cach sme sa zamerali na dve komplement\u00e1rne realiz\u00e1cie tak\u00fdchto syst\u00e9mov: lokalizovan\u00fdch fermi\u00f3nov na trojuholn\u00edkovej mrie\u017eke a kone\u010dn\u00e9 kvantov\u00e9 klastre reprezentuj\u00face molekul\u00e1rne magnety. Monte Carlo simul\u00e1cie fermi\u00f3nov\u00e9ho modelu s lok\u00e1lnou hubbardovskou interakciou a isingovskou najbli\u017e\u0161ou v\u00fdmennou interakciou ukazuj\u00fa, \u017ee kombin\u00e1cia geometrickej frustr\u00e1cie a elektr\u00f3nov\u00fdch korel\u00e1ci\u00ed vedie k z\u00e1sadne odli\u0161n\u00e9mu spr\u00e1vaniu pre feromagnetick\u00fa a antiferomagnetick\u00fa interakciu. Na rozdiel od te\u00f3rie stredn\u00e9ho po\u013ea, ktor\u00e1 predpoved\u00e1 kvalitat\u00edvne podobn\u00e9 spr\u00e1vanie v oboch pr\u00edpadoch, numerick\u00e9 simul\u00e1cie odha\u013euj\u00fa v\u00fdrazn\u00e9 potla\u010denie \u010falekodosahov\u00e9ho usporiadania v antiferomagnetickom pr\u00edpade a zmeny charakteru f\u00e1zov\u00fdch prechodov v d\u00f4sledku fluktu\u00e1ci\u00ed. V druhej \u010dasti analyzujeme vplyv ve\u013ekosti klastra, geometrie a interakci\u00ed na magnetokalorick\u00e9 chladenie. V spinovom Heisenbergovom modeli sa najsilnej\u0161\u00ed chladiaci efekt objavuje v Isingovej limite a pre mal\u00e9 klastre, zatia\u013e \u010do v Hubbardovom modeli je rozhoduj\u00faca rovnov\u00e1ha medzi lokaliz\u00e1ciou a itineranciou elektr\u00f3nov a optim\u00e1lny re\u017eim sa nach\u00e1dza pri stredn\u00fdch hodnot\u00e1ch interakcie elektr\u00f3nov. Tak\u00fdto systematick\u00fd pr\u00edstup otv\u00e1ra cestu k dizajnu re\u00e1lnych materi\u00e1lov s optimalizovan\u00fdmi magnetokalorick\u00fdmi vlastnos\u0165ami.<\/p>\n <\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n <\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 Streda <\/span>22.10.2025 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n Supertekut\u00e9 3He ako univerz\u00e1lny modelov\u00fd syst\u00e9m pre kvantov\u00fa fyziku<\/strong><\/a><\/p>\n <\/p>\n RNDr. Peter Skyba, DrSc.<\/strong><\/p>\n Centrum fyziky n\u00edzkych tepl\u00f4t \u00daEF SAV, v. v. i. <\/p>\n Anot\u00e1cia:<\/strong><\/p>\n Supratekut\u00e9 h\u00e9lium-3 je jedine\u010dn\u00fd fyzik\u00e1lny syst\u00e9m s najkomplexnej\u0161\u00edm f\u00e1zov\u00fdm prechodom, pri ktorom sa nar\u00fa\u0161a celkovo \u0161es\u0165 symetri\u00ed (orbit\u00e1lna, spinov\u00e1, kalibra\u010dn\u00e1, symetria \u010dasovej inverzie, parita\/chiralita a n\u00e1bojov\u00e1 symetria). Tento fakt \u201erob\u00ed\u201c zo\u00a0 supratekut\u00e9ho h\u00e9lia-3 unik\u00e1tne experiment\u00e1lne laborat\u00f3rium resp. modelov\u00fd syst\u00e9m na testovanie mnoh\u00fdch fyzik\u00e1lnych hypot\u00e9z a te\u00f3rii, vr\u00e1tane t\u00fdch kvantov\u00fdch.<\/p>\n Jednou z v\u00fdnimo\u010dn\u00fdch fyzik\u00e1lnych vlastnost\u00ed supratekut\u00fdch f\u00e1z h\u00e9lia-3 je pr\u00edtomnos\u0165 tzv. magnetickej supratekutosti, ktorej prejavom s\u00fa supratekut\u00e9 spinov\u00e9 toky. Experiment\u00e1lnym d\u00f4kazom tejto magnetickej supratekutosti je cel\u00e1 paleta r\u00f4znych stavov s koherentnou precesiou spinov. Tieto stavy s koherentnou precesiou spinov je naviac mo\u017eno pova\u017eova\u0165 aj za Bose-Einsteinov kondenz\u00e1t magn\u00f3nov, t. j. syst\u00e9m kolekt\u00edvnych excit\u00e1ci\u00ed, ktor\u00e9 sa nach\u00e1dzaj\u00fa v kvantovom koherentnom stave. Cie\u013eom predn\u00e1\u0161ky je obozn\u00e1mi\u0165 posluch\u00e1\u010dov so z\u00e1kladn\u00fdmi fyzik\u00e1lnymi vlastnos\u0165ami supratekut\u00fdch f\u00e1z h\u00e9lia-3, najm\u00e4 z poh\u013eadu magnetickej supratekutosti, vysvetli\u0165 fyzik\u00e1lnu podstatu spont\u00e1nneho formovania stavov s koherentnou precesiou spinov, ako tieto stavy m\u00f4\u017eu by\u0165 pou\u017eit\u00e9 k modelovaniu tzv. \u201eGoldstonovsk\u00fdch\u201c resp. \u201eneGoldstonovsk\u00fdch\u201c oscila\u010dn\u00fdch m\u00f3dov a prezentova\u0165 jednu z mo\u017en\u00fdch aplik\u00e1ci\u00ed t\u00fdchto stavov ako kvantov\u00e9ho rezonan\u010dn\u00e9ho zosil\u0148ova\u010da pracuj\u00faceho na novom fyzik\u00e1lnom princ\u00edpe. Z\u00e1verom predn\u00e1\u0161ky predostriem bud\u00facnos\u0165 v\u00fdskumu a vyu\u017eitia supratekut\u00fdch f\u00e1z h\u00e9lia-3 z h\u013eadiska jeho mo\u017en\u00e9ho vyu\u017eitia ako modelov\u00e9ho syst\u00e9mu pre kvantov\u00fa fyziku.<\/p>\n <\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 Streda <\/span>25.06.2025 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n Vplyv vy\u0161\u0161\u00edch korel\u00e1ci\u00ed turbulentn\u00e9ho r\u00fdchlostn\u00e9ho po\u013ea na anom\u00e1lne \u0161k\u00e1lovanie v turbulentnej kinematickej magnetohydrodynamike<\/strong><\/a><\/p>\n <\/p>\n RNDr. Richard Remeck\u00fd, PhD.<\/strong><\/p>\n Oddelenie teoretickej fyziky \u00daEF SAV, v. v. i. <\/p>\n Anot\u00e1cia:<\/strong><\/p>\n Fundament\u00e1lne pochopenie vlastnost\u00ed a javov prebiehaj\u00facich v \u00faplne rozvinut\u00fdch turbulentn\u00fdch syst\u00e9moch ost\u00e1va aj v dne\u0161nej dobe jedn\u00fdm z nevyrie\u0161en\u00fdch probl\u00e9mov s\u00fa\u010dasnej teoretickej fyziky. Matematick\u00e1 zlo\u017eitos\u0165 stochastick\u00fdch diferenci\u00e1lnych rovn\u00edc, ktor\u00e9 dok\u00e1\u017eu adekv\u00e1tne op\u00edsa\u0165 zlo\u017eit\u00fd chaotick\u00fd charakter pr\u00edslu\u0161n\u00fdch turbulentn\u00fdch pr\u00faden\u00ed, ako napr\u00edklad stochastick\u00e1 Navier-Stokesova rovnica, neumo\u017e\u0148uje n\u00e1js\u0165 uzavret\u00e9 analytick\u00e9 rie\u0161enia ani v t\u00fdch najjednoduch\u0161\u00edch pr\u00edpadoch. Jedn\u00fdm z mo\u017en\u00fdch pr\u00edstupov k anal\u00fdze modelov plne rozvinutej turbulencie je tzv. teoreticko-po\u013eov\u00e1 renormaliza\u010dn\u00e1 grupa, ktor\u00e1 umo\u017e\u0148uje ich systematick\u00e9 teoretick\u00e9 \u0161t\u00fadium v r\u00f4znych r\u00e1doch zodpovedaj\u00facej poruchovej te\u00f3rie.<\/p>\n V tomto oh\u013eade, budeme v prezentovanej pr\u00e1ci met\u00f3dami teoreticko-po\u013eovej RG v druhom r\u00e1de poruchov\u00e9ho po\u010dtu detailne \u0161tudova\u0165 vlastnosti anom\u00e1lneho \u0161k\u00e1lovania korela\u010dn\u00fdch funkci\u00ed slab\u00e9ho n\u00e1hodn\u00e9ho magnetick\u00e9ho po\u013ea v kinematickej magnetohydrodynamickej (MHD) turbulencii, t.j., magnetick\u00e9ho po\u013ea v elektricky vodivom turbulentnom prostred\u00ed op\u00edsanom stochastickou Navier-Stokesovou rovnicou. Z\u00edskan\u00e9 v\u00fdsledky bud\u00fa porovnan\u00e9 s v\u00fdsledkami z\u00edskan\u00fdmi v r\u00e1mci tzv. Kazantsev-Kraichnanovho modelu kinematickej turbulentnej MHD, v r\u00e1mci ktorej \u0161tatistika turbulentn\u00e9ho r\u00fdchlostn\u00e9ho po\u013ea m\u00e1 gaussovsk\u00fd charakter. T\u00e1to anal\u00fdza n\u00e1m umo\u017e\u0148uje n\u00e1js\u0165 vplyv vy\u0161\u0161\u00edch korel\u00e1ci\u00ed turbulentn\u00e9ho r\u00fdchlostn\u00e9ho po\u013ea, dan\u00fdch stochastickou Navier-Stokesovou rovnicou, na kritick\u00e9 exponenty korela\u010dn\u00fdch funkci\u00ed pas\u00edvne advektovan\u00e9ho magnetick\u00e9ho po\u013ea, ako aj na zachovanie mo\u017enej ve\u013eko-\u0161k\u00e1lovej anizotropie hlboko vn\u00fatri tzv. inerci\u00e1lneho intervalu.<\/p>\n <\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 \u0160tvrtok<\/span>\u00a024.04.2025 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n Proximity effect of correlated electronic states of 1T-TaS2 on graphene<\/strong><\/a><\/p>\n <\/p>\n RNDr. Martin Gmitra, PhD.<\/strong><\/p>\n Centrum fyziky n\u00edzkych tepl\u00f4t \u00daEF SAV, v. v. i. Anot\u00e1cia:<\/strong><\/p>\n Proximity-induced effects in graphene-based van der Waals heterostructures have been shown to provide an efficient way to tune graphene’s low-energy electronic states [1]. Transition metal dichalcogenide 1T-TaS2 exhibits a variety of periodic lattice distortions, triggering a stable low-temperature periodic charge density wave with a David star pattern and magnetic ground state in the monolayer limit. In the talk, we will discuss proximity-induced effects such as spin-orbit coupling and exchange interaction in graphene on monolayer 1T-TaS2 using density functional theory and tight-binding modeling [2]. Using the effective tight-binding model, the charge to spin conversion efficiency using the linear Kubo response approach and the self-induced torque within the nonequilibrium Green\u2019s function transport will be presented.<\/p>\n [1] K. Zollner, M. Kurpas, M. Gmitra, J. Fabian, Nature Reviews Physics (2025). <\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 \u0160tvrtok<\/span>\u00a020.02.2025 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n Stavy s vlastnos\u0165ami spinov\u00fdch kvapal\u00edn v antiferomagnetick\u00fdch syst\u00e9moch s kagome \u0161trukt\u00farou<\/strong><\/a><\/p>\n <\/p>\n RNDr. Mari\u00e1n Jur\u010di\u0161in, PhD.<\/strong><\/p>\n Oddelenie teoretickej fyziky \u00daEF SAV, v. v. i. Anot\u00e1cia:<\/strong><\/p>\n Magnetick\u00e9 a termodynamick\u00e9 vlastnosti interak\u010dne anizotropn\u00fdch antiferomagnetick\u00fdch syst\u00e9mov na tzv. square-kagome mrie\u017eke s\u00fa vy\u0161etrovan\u00e9 v r\u00e1mci exaktne rie\u0161ite\u013en\u00e9ho modelu na pr\u00edslu\u0161nej rekurz\u00edvnej mrie\u017eke. F\u00e1zov\u00fd diagram modelu je n\u00e1jden\u00fd a f\u00e1zov\u00e9 prechody medzi r\u00f4znymi f\u00e1zami s\u00fa identifikovan\u00e9. V z\u00e1vislosti od parametrov modelu je uk\u00e1zan\u00e1 mo\u017enos\u0165 existencie r\u00f4znych vysoko-degenerovan\u00fdch z\u00e1kladn\u00fdch stavov s evidentnou pr\u00edtomnos\u0165ou typick\u00fdch vlastnost\u00ed spinov\u00fdch kvapal\u00edn. Rezidu\u00e1lne entropie v\u0161etk\u00fdch z\u00e1kladn\u00fdch stavov modelu s\u00fa n\u00e1jden\u00e9 a ich spinov\u00e1 \u0161trukt\u00fara je diskutovan\u00e1. Vplyv pr\u00edtomnosti diskr\u00e9tnej hierarchie rezidu\u00e1lnych entropi\u00ed z\u00e1kladn\u00fdch stavov modelu na anom\u00e1lne spr\u00e1vanie sa mern\u00e9ho tepla pri n\u00edzkych teplot\u00e1ch je taktie\u017e analyzovan\u00fd.<\/p>\n <\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 \u0160tvrtok<\/span>\u00a021.11.2024 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n Proteomick\u00e1 \u0161t\u00fadia pancientok s rakovinou prsn\u00edka<\/strong><\/a><\/p>\n <\/p>\n RNDr. Martin Menkyna, PhD.<\/strong><\/p>\n \u00dastav lek\u00e1rskej a klinickej biofyziky LF UPJ\u0160 Anot\u00e1cia:<\/strong><\/p>\n Rakovina prsn\u00edka je naj\u010dastej\u0161ou onkologickou diagn\u00f3zou u \u017eien a ke\u010f\u017ee sa rakovina ako tak\u00e1 rad\u00ed medzi prv\u00e9 dve najroz\u0161\u00edrenej\u0161ie pr\u00ed\u010diny smrti medzi \u017eenami, je potrebn\u00e9 jej venova\u0165 patri\u010dn\u00fa pozornos\u0165 aj z toho d\u00f4vodu, \u017ee moment\u00e1lne fin\u00e1lnym pos\u00faden\u00edm jej pr\u00edtomnosti je invaz\u00edvna biopsia. Cie\u013eom semin\u00e1ra bude predstavi\u0165 proteomiku ako \u0161pi\u010dkov\u00fa met\u00f3du na v\u00fdskum rakoviny so zrete\u013eom na jej aplik\u00e1ciu vo v\u00fdskume diagnostiky rakoviny prsn\u00edka, jej v\u00fdhody, ako aj \u0165a\u017ekosti spojen\u00e9 s klinick\u00fdm v\u00fdskumom. Konkr\u00e9tne sa pozrieme na \u0161t\u00fadie zaoberaj\u00face sa h\u013eadan\u00edm potencion\u00e1lnych biomarkerov pri r\u00f4znych typov rakoviny prsn\u00edka (Luminal A, Luminal B, ben\u00edgne a triple negat\u00edvny) z\u00edskan\u00fdch porovnan\u00edm prote\u00f3mu pacientiek so zdravou popul\u00e1ciou.<\/p>\n <\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 \u0160tvrtok<\/span>\u00a003.10.2024 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n Spin-orbital effects in nanostructures<\/strong><\/a><\/p>\n <\/p>\n RNDr. Michal Pudl\u00e1k, CSc.<\/strong><\/p>\n Oddelenie biofyziky \u00daEF SAV, v. v. i. Anot\u00e1cia:<\/strong><\/p>\n Graphen corrugations affect the hybridization of orbitals of carbon atoms in graphene-based systems. As a result, the momentum distribution of electrons can be selected without external electric and magnetic fields in the graphene strip under experimentally feasible periodic potential created by the ripple structure in graphene. This potential is used to produce the valley-depending focusing effects and spin filtering effects. We also describe the electron transport through a onedimensional quantum ring, subjected to Rashba spin-orbit interaction in the presence of external fields. We show specific conditions to reach the spin filtering effect in such a system.<\/p>\n <\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 \u0160tvrtok<\/span>\u00a020.06.2024 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n Kolekt\u00edvne javy v syst\u00e9moch so zmie\u0161anou valen\u010dnos\u0165ou<\/strong><\/a><\/p>\n <\/p>\n RNDr. Pavol Farka\u0161ovsk\u00fd, DrSc<\/strong>.<\/p>\n Oddelenie teoretickej fyziky \u00daEF SAV, v. v. i. Anot\u00e1cia:<\/strong><\/p>\n Interakcie medzi elektr\u00f3nmi v kombin\u00e1cii s Pauliho vylu\u010dovac\u00edm princ\u00edpom ved\u00fa v multikomponentn\u00fdch syst\u00e9moch fermi\u00f3nov k ich kolekt\u00edvnemu spr\u00e1vaniu, ktor\u00e9 rezultuje v cel\u00fd rad zauj\u00edmav\u00fdch fyzik\u00e1lnych javov ako s\u00fa prechody kov-izol\u00e1tor, valen\u010dn\u00e9 prechody, itinerantn\u00fd feromagnetizmus, nehomog\u00e9nne n\u00e1bojov\u00e9 usporiadania, elektr\u00f3nov\u00fd feroelektrick\u00fd jav \u010di supravodivos\u0165. Tieto kolekt\u00edvne javy s\u00fa pozorovan\u00e9 v \u0161irokej triede materi\u00e1lov zahr\u0148uj\u00facich zl\u00fa\u010deniny prechodov\u00fdch kovov a vz\u00e1cnych zem\u00edn (kupr\u00e1ty, kobalt\u00e1ty, mangan\u00e1ty, hexaboridy …) a ich jednotn\u00fd popis predstavuje st\u00e1le ve\u013ek\u00fa v\u00fdzvu pre s\u00fa\u010dasn\u00fa te\u00f3riu kondenzovan\u00fdch l\u00e1tok. V predn\u00e1\u0161ke sa zameriam na diskusiu \u0161tyroch okruhov probl\u00e9mov s\u00favisiacich s kolekt\u00edvnymi javmi v syst\u00e9moch so zmie\u0161anou valen\u010dnos\u0165ou: (i) Popis tlakom indukovan\u00fdch valen\u010dn\u00fdch prechodov a prechodov kov-izol\u00e1tor, (ii) Generovanie viazan\u00fdch d a f elektr\u00f3nov\u00fdch p\u00e1rov (excit\u00f3nov) a ich kondenz\u00e1cia, (iii) Formovanie nehomog\u00e9nneho n\u00e1bojov\u00e9ho usporiadania a (iv) Vz\u0165ahu medzi nehomog\u00e9nnym n\u00e1bojov\u00fdm usporiadan\u00edm a supravodivos\u0165ou. Z\u00edskan\u00e9 teoretick\u00e9 v\u00fdsledky bud\u00fa na z\u00e1ver konfrontovan\u00e9 s experiment\u00e1lnymi meraniami v re\u00e1lnych syst\u00e9moch so zmie\u0161anou valen\u010dnos\u0165ou.<\/p>\n <\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 Streda<\/span>\u00a010.04.2024 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n Efekt\u00edvnos\u0165 techniky rekurz\u00edvnych mrie\u017eok pre \u0161t\u00fadium <\/p>\n RNDr. Eva Jur\u010di\u0161inov\u00e1, PhD.<\/strong><\/p>\n Oddelenie teoretickej fyziky \u00daEF SAV, v. v. i. Anot\u00e1cia:<\/strong><\/p>\n Je zaveden\u00e1 vy\u0161\u0161ia rekurz\u00edvna aproxim\u00e1cia pyrochlorovej mrie\u017eky, ktor\u00e1 berie do \u00favahy jej typick\u00fa geometrick\u00fa \u0161trukt\u00faru pozost\u00e1vaj\u00facu z cyklick\u00e9ho usporiadania \u0161iestich element\u00e1rnych tetra\u00e9drov. Relevantnos\u0165 a efektivita takto zavedenej rekurz\u00edvnej mrie\u017eky pre \u0161t\u00fadium feromagnetick\u00fdch ako aj antiferomagnetick\u00fdch syst\u00e9mov s pyrochlorovou \u0161trukt\u00farou je analyzovan\u00e1 v r\u00e1mci klasick\u00e9ho Isingovho modelu vo vonkaj\u0161om magnetickom poli. Je odvoden\u00fd explicitn\u00fd analytick\u00fd tvar vo\u013enej energie modelu na jeden uzol mrie\u017eky, a teda je uk\u00e1zan\u00e9, \u017ee model je matematicky exaktne rie\u0161ite\u013en\u00fd. Magnetiza\u010dn\u00e9 a entropick\u00e9 vlastnosti v\u0161etk\u00fdch z\u00e1kladn\u00fdch stavov antiferomagnetick\u00e9ho modelu s\u00fa n\u00e1jden\u00e9 a porovnan\u00e9 s vlastnos\u0165ami z\u00edskan\u00fdmi v r\u00e1mci ni\u017e\u0161ej rekurz\u00edvnej aproxim\u00e1cie modelu na tzv. tetra\u00e9drickej rekurz\u00edvnej mrie\u017eke. Je uk\u00e1zan\u00e9, \u017ee zn\u00e1ma Paulingova entropia pre vodn\u00fd \u013ead nem\u00f4\u017ee predstavova\u0165 skuto\u010dn\u00fa rezidu\u00e1lnu entropiu antiferomagnetick\u00e9ho syst\u00e9mu na regul\u00e1rnej pyrochlorovej mrie\u017eke v nulovom magnetickom poli. Bude tie\u017e diskutovan\u00e9 zlep\u0161enie hodnoty kritickej teploty feromagnetick\u00e9ho modelu na pyrochlorovej mrie\u017eke z\u00edskanej v r\u00e1mci zavedenej vy\u0161\u0161ej rekurz\u00edvnej aproxim\u00e1cie. Anal\u00fdzou z\u00edskan\u00fdch v\u00fdsledkov bude uk\u00e1zan\u00e1 vysok\u00e1 efekt\u00edvnos\u0165 rekurz\u00edvnych aproxim\u00e1ci\u00ed pre \u0161t\u00fadium magnetick\u00fdch syst\u00e9mov s pyrochlorovou \u0161trukt\u00farou, predov\u0161etk\u00fdm syst\u00e9mov s pr\u00edtomnos\u0165ou geometrickej frustr\u00e1cie.<\/p>\n <\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 Streda<\/span>\u00a014.02.2024 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n Renormaliza\u010dn\u00e1 grupa v stochastickej dynamike: RNDr. Richard Remeck\u00fd, PhD.<\/strong><\/p>\n Oddelenie teoretickej fyziky \u00daEF SAV, v. v. i. Anot\u00e1cia:\u00a0<\/strong><\/p>\n \u0160t\u00fadium vlastnost\u00ed turbulentn\u00fdch syst\u00e9mov sa v poslednom \u010dase te\u0161\u00ed zna\u010dn\u00e9mu experiment\u00e1lnemu a teoretick\u00e9mu z\u00e1ujmu. V oblasti te\u00f3rie je tento z\u00e1ujem spojen\u00fd hlavne so zdokonalen\u00edm v\u00fdpo\u010dtov\u00fdch met\u00f3d ako aj so samotn\u00fdm n\u00e1rastom v\u00fdkonu po\u010d\u00edta\u010dov, ktor\u00fd umo\u017e\u0148uje simulovanie komplexnej\u0161\u00edch turbulentn\u00fdch syst\u00e9mov pre relat\u00edvne ve\u013ek\u00e9 hodnoty Reynoldsovho \u010d\u00edsla (\ud835\udc45\ud835\udc52). V tejto predn\u00e1\u0161ke sa v\u0161ak vyd\u00e1me in\u00fdm smerom a predstav\u00edme mo\u017enosti analytick\u00e9ho pr\u00edstupu k \u0161t\u00fadiu turbulentn\u00fdch syst\u00e9mov met\u00f3dami tzv. po\u013eovoteoretickej renormaliza\u010dnej grupy (RG).<\/p>\n V prvej \u010dasti predn\u00e1\u0161ky si v kr\u00e1tkosti predstav\u00edme matematick\u00e9 postupy te\u00f3rie po\u013ea pri \u0161t\u00fadiu turbulentn\u00fdch syst\u00e9mov v limite \ud835\udc45\ud835\udc52 \u2192 \u221e. Uk\u00e1\u017eeme, ako n\u00e1m matematick\u00fd apar\u00e1t RG umo\u017e\u0148uje analyticky \u0161tudova\u0165 niektor\u00e9 fyzik\u00e1lne aspekty plne rozvinutej turbulencie v modeloch skal\u00e1rnych ako aj vektorov\u00fdch pr\u00edmes\u00ed s r\u00f4zne definovan\u00fdmi \u0161tatistikami r\u00fdchlostn\u00fdch pol\u00ed riadiacich dynamiku \u0161tudovan\u00fdch modelov.<\/p>\n Druh\u00fa \u010das\u0165 predn\u00e1\u0161ky venujeme podrobnej\u0161iemu predstaveniu vyu\u017eitia RG met\u00f3d pri \u0161t\u00fadiu anom\u00e1lneho \u0161k\u00e1lovania korela\u010dn\u00fdch funkci\u00ed magnetick\u00e9ho po\u013ea v modeli kinematickej magnetohydrodynamiky, kde stochasticita syst\u00e9mu je dan\u00e1 rie\u0161en\u00edm stochastickej Navier-Stokesovej rovnice pre r\u00fdchlostn\u00e9 pole a kinematick\u00fd re\u017eim zabezpe\u010duje pasivitu magnetick\u00e9ho po\u013ea vzh\u013eadom na r\u00fdchlostn\u00e9 pole (tzv. Lorentzova sila sa v tomto pr\u00edpade zanedb\u00e1va). V z\u00e1vere uk\u00e1\u017eeme \u0161k\u00e1lovanie korela\u010dn\u00fdch funkci\u00ed magnetick\u00e9ho po\u013ea a porovn\u00e1me ho s r\u00f4znymi modelmi plne rozvinutej turbulencie v druhom r\u00e1de poruchov\u00e9ho po\u010dtu.<\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 Pondelok<\/span>\u00a027.11.2023 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n \u0164a\u017ek\u00e9 kvark\u00f3nia ako sonda jadrov\u00fdch efektov vo foto-jadrov\u00fdch reakci\u00e1ch<\/strong><\/a><\/p>\n Doc. RNDr. J\u00e1n Nem\u010d\u00edk, CSc.<\/strong><\/p>\n Oddelenie teoretickej fyziky \u00daEF SAV, v. v. i. Anot\u00e1cia:<\/strong><\/p>\n \u0164a\u017ek\u00e9 kvark\u00f3nia, produkovan\u00e9 v reakci\u00e1ch indukovan\u00fdch fot\u00f3nmi, predstavuj\u00fa ve\u013emi\u00a0 efekt\u00edvny n\u00e1stroj pre \u0161t\u00fadium r\u00f4znych QCD efektov. V r\u00e1mci QCD formalizmu farebn\u00e9ho dip\u00f3lu analyzujeme nasledovn\u00e9 javy: Na\u0161e v\u00fdpo\u010dty diferenci\u00e1lnych \u00fa\u010dinn\u00fdch prierezov s\u00fa v dobrej zhode so s\u00fa\u010dasn\u00fdmi experiment\u00e1lnymi \u00fadajmi kolabor\u00e1cie ALICE o produkcii \u0161arm\u00f3ni\u00ed v jadrov\u00fdch ultraperifer\u00e1lnych zr\u00e1\u017ekach. Uv\u00e1dzame tie\u017e predpovede pre koherentn\u00fa foto-produkciu in\u00fdch stavov kvark\u00f3ni\u00ed (\u03c8\u2032(2S), \u03a5(1S) a \u03a5\u2032(2S)), ktor\u00e9 m\u00f4\u017eu by\u0165 overen\u00e9 bud\u00facimi meraniami na ur\u00fdch\u013eova\u010di LHC.<\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 \u0160tvrtok<\/span>\u00a019.10.2023 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n Prenos excit\u00f3nu medzi ant\u00e9nnym komplexom LH1 a dim\u00e9rom fotosyntetick\u00e9ho reak\u010dn\u00e9ho centra<\/strong><\/a><\/p>\n RNDr. Richard Pin\u010d\u00e1k, PhD.<\/strong><\/p>\n Oddelenie teoretickej fyziky \u00daEF SAV, v. v. i. Anot\u00e1cia:<\/strong><\/p>\n Fotosynt\u00e9za je proces, pri ktorom sa energia slne\u010dn\u00e9ho \u017eiarenia premie\u0148a na chemick\u00fa energiu a potom sa uklad\u00e1 v biologick\u00fdch syst\u00e9moch. Ide o kvantov\u00fd proces vyu\u017e\u00edvaj\u00faci energiu fot\u00f3nov na pohyb elektr\u00f3nu a synt\u00e9zu vysokoenergetick\u00fdch chemick\u00fdch zl\u00fa\u010den\u00edn. Energiu slne\u010dn\u00e9ho \u017eiarenia zachyt\u00e1vaj\u00fa pigmenty bakteriochlorofylu a t\u00e1to energia sa s vysokou \u00fa\u010dinnos\u0165ou pren\u00e1\u0161a do fotosyntetick\u00e9ho reak\u010dn\u00e9ho centra v ktorom s\u00fa pigmenty organizovan\u00e9 do prstencovej \u0161trukt\u00fary naz\u00fdvanej ant\u00e9nny komplex. Na pr\u00edklade fotosyntetick\u00fdch reak\u010dn\u00fdch centier je uk\u00e1zan\u00e9, \u017ee prenos elektr\u00f3nov na cie\u013eov\u00e9 miesto m\u00f4\u017ee by\u0165 riaden\u00fd vibra\u010dn\u00fdmi re\u017eimami, kde sa elektr\u00f3n lokalizuje. V pr\u00edpade reak\u010dn\u00fdch centier s\u00fa to n\u00edzke vibra\u010dn\u00e9 re\u017eimy, ktor\u00e9 vytv\u00e1raj\u00fa tak\u00fdto efekt. Predpoklad\u00e1me, \u017ee prich\u00e1dzaj\u00faca energia excituje elektr\u00f3n z n\u00edzkoenergetick\u00e9ho stavu do vysokoenergetick\u00e9ho excitovan\u00e9ho stavu. N\u00e1sledne za\u010d\u00edna reakcia prenosu elektr\u00f3nov, kde elektr\u00f3n-vibra\u010dn\u00e1 v\u00e4zba hr\u00e1 d\u00f4le\u017eit\u00fa \u00falohu pri prenose.<\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n <\/p>\n \u2022<\/span><\/span>\u00a0 Streda<\/span>\u00a014.06.2023 <\/span><\/span>o 11:00 hod.<\/span>\u00a0 Sal\u00f3nik \u00daEF, Watsonova 47, Ko\u0161ice<\/strong><\/p>\n <\/p>\n \u0160t\u00fadium spinovo-elektr\u00f3nov\u00fdch modelov na Shastryho-Sutherlandovej mrie\u017eke<\/strong><\/a><\/span><\/p>\n RNDr. \u013dubom\u00edra Regeciov\u00e1, PhD.<\/strong><\/p>\n Oddelenie teoretickej fyziky \u00daEF SAV, v. v. i. Anot\u00e1cia:<\/strong><\/p>\n V ned\u00e1vnych pr\u00e1cach sme navrhli nov\u00e9 modely (komplexn\u00fd spinovo-elektr\u00f3nov\u00fd model, efekt\u00edvny Coupled double-Ising model) pre popis magnetiza\u010dn\u00fdch vlastnost\u00ed a termodynamiky tetraboridov vz\u00e1cnych zem\u00edn (RB4), ktor\u00e9 na rozdiel od predch\u00e1dzaj\u00facich modelov zoh\u013ead\u0148uj\u00fa r\u00f4zne ve\u013ekosti spinov v spinovom a elektr\u00f3novom podsyst\u00e9me, hubbardovsk\u00fa interakciu a interakciu medzi t\u00fdmito podsyst\u00e9mami. Na\u0161e numerick\u00e9 simul\u00e1cie uk\u00e1zali, \u017ee kombin\u00e1cia t\u00fdchto faktorov m\u00e1 ve\u013ek\u00fd potenci\u00e1l objasni\u0165 absenciu 1\/3 magnetiza\u010dnej zdr\u017ee (pozorovanej v Isingovom modeli a vo viacer\u00fdch jeho zov\u0161eobecneniach) a formovanie jedinej 1\/2 zdr\u017ee, ktor\u00e1 bola pozorovan\u00e1 v magnetiza\u010dn\u00fdch krivk\u00e1ch TmB4 a ErB4. Ve\u013emi dobr\u00e1 zhoda medzi teoretick\u00fdmi a experiment\u00e1lnymi v\u00fdsledkami bola n\u00e1jden\u00e1 aj pre pr\u00edpad teplotn\u00fdch z\u00e1vislost\u00ed tepelnej kapacity, v ktorej sa formovalo n\u00edzkoteplotn\u00e9 maximum odpovedaj\u00face elektr\u00f3nov\u00e9mu podsyst\u00e9mu nasledovan\u00e9 \u010fal\u0161\u00edm maximom spinov\u00e9ho podsyst\u00e9mu, ako aj oblast\u00ed chladenia a ohrevov v pr\u00edpade magnetokalorick\u00e9ho efektu. \u010eal\u0161ou v\u00fdhodou t\u00fdchto modelov je fakt, \u017ee ich pou\u017eitie je pomerne \u0161irok\u00e9 a po optimaliz\u00e1cii parametrov ich bude mo\u017en\u00e9 pou\u017ei\u0165 aj na popis \u010fal\u0161\u00edch kovov\u00fdch magnetov.<\/p>\n Pozv\u00e1nka<\/a><\/p>\n <\/p>\n
\nOd fermi\u00f3nov na trojuholn\u00edkovej mrie\u017eke k molekul\u00e1rnym magnetom<\/strong><\/a><\/p>\n
\nregeciova@saske.sk<\/p>\n
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\n2025:<\/strong><\/h3>\n
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\nskyba@saske.sk<\/p>\n
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\nremecky@saske.sk<\/p>\n
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\ngmitra@saske.sk<\/p>\n
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\n[2] K. Szalowski, M. Milivojevi\u0107, D. Kochan. M. Gmitra, 2D Materials 10, 025013 (2023).<\/p>\n
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\njurcisin@saske.sk<\/p>\n
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\n2024:<\/strong><\/h3>\n
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\nmartin.menkyna@upjs.sk<\/p>\n
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\npudlak@saske.sk<\/p>\n
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\nfarky@saske.sk<\/p>\n
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\nmagnetick\u00fdch syst\u00e9mov s pyrochlorovou \u0161trukt\u00farou<\/strong><\/a><\/p>\n
\njurcisine@saske.sk<\/p>\n
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\nAnom\u00e1lne \u0161k\u00e1lovanie pas\u00edvnych pr\u00edmes\u00ed<\/strong><\/a><\/p>\n
\nremecky@saske.sk<\/p>\n
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\n2023:<\/strong><\/h3>\n
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\nnemcik@saske.sk<\/p>\n
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\ni) Korel\u00e1ciu medzi zr\u00e1\u017ekov\u00fdm parametrom a orient\u00e1ciou dip\u00f3lu;
\nii) Vy\u0161\u0161\u00ed twist jadrov\u00e9ho tienenia s\u00favisiaci s najni\u017e\u0161\u00edm Fockovsk\u00fdm stavom fot\u00f3nu obsahuj\u00facim kvark a antikvark;
\niii) Ved\u00faci twist glu\u00f3nov\u00e9ho tienenia odpovedaj\u00faci vy\u0161\u0161\u00edm Fockovsk\u00fdm komponentom fot\u00f3nu obsahuj\u00facim glu\u00f3ny;
\niv) Redukovan\u00e9 efekty kvantovej koherencie v popul\u00e1rnej Balitsky-Kovchegovovej evolu\u010dnej rovnici v porovnan\u00ed so s\u00fa\u010dasn\u00fdmi v\u00fdpo\u010dtami, ktor\u00e9 s\u00fa \u010dasto uverej\u0148ovan\u00e9 v literat\u00fare.<\/p>\n
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\npincak@saske.sk<\/p>\n
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