TY - JOUR AU - Vajtai, Lili AU - Nemes, Norbert Marcel AU - Morales, Maria del Puerto AU - Molnár, Kolos AU - Pinke, Balazs Gabor AU - Simon, Ferenc TI - Incidence of the Brownian Relaxation Process on the Magnetic Properties of Ferrofluids JF - NANOMATERIALS J2 - NANOMATERIALS-BASEL VL - 14 PY - 2024 IS - 7 PG - 15 SN - 2079-4991 DO - 10.3390/nano14070634 UR - https://m2.mtmt.hu/api/publication/34801218 ID - 34801218 N1 - Department of Physics, Institute of Physics, HUN-REN-BME Condensed Matter Research Group, Budapest University of Technology and Economics, Műegyetem rkp. 3., Budapest, H-1111, Hungary Departamento de Física de Materiales, Universidad Complutense de Madrid, Madrid, 28040, Spain Department of Nanoscience and Nanotechnology, Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Madrid, 28049, Spain Department of Polymer Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Műegyetem rkp. 3., Budapest, H-1111, Hungary HUN–REN–BME Research Group for Composite Science and Technology, Műegyetem rkp. 3., Budapest, H-1111, Hungary MTA-BME Lendület Sustainable Polymers Research Group, Műegyetem rkp. 3., Budapest, H-1111, Hungary Institute for Solid State Physics and Optics, HUN-REN Wigner Research Centre for Physics, P.O. Box 49, Budapest, H-1525, Hungary Export Date: 22 April 2024 Correspondence Address: Nemes, N.M.; Departamento de Física de Materiales, Spain; email: nmnemes@ucm.es AB - Ferrofluids containing magnetic nanoparticles represent a special class of magnetic materials due to the added freedom of particle tumbling in the fluids. We studied this process, known as Brownian relaxation, and its effect on the magnetic properties of ferrofluids with controlled magnetite nanoparticle sizes. For small nanoparticles (below 10 nm diameter), the Neel process is expected to dominate the magnetic response, whereas for larger particles, Brownian relaxation becomes important. Temperature- and magnetic-field-dependent magnetization studies, differential scanning calorimetry, and AC susceptibility measurements were carried out for 6 and 13.5 nm diameter magnetite nanoparticles suspended in water. We identify clear fingerprints of Brownian relaxation for the sample of large-diameter nanoparticles as both magnetic and thermal hysteresis develop at the water freezing temperature, whereas the samples of small-diameter nanoparticles remain hysteresis-free down to the magnetic blocking temperature. This is supported by the temperature-dependent AC susceptibility measurements: above 273 K, the data show a low-frequency Debye peak, which is characteristic of Brownian relaxation. This peak vanishes below 273 K. LA - English DB - MTMT ER - TY - JOUR AU - Fürjes, Bálint AU - Dóra, Balázs AU - Simon, Ferenc TI - Az elektromágneses sugárzás távolhatása, avagy mire jó a Poynting-vektor; illetve tudunk-e a fénynél gyorsabban haladó jeleket előállítani? JF - FIZIKAI SZEMLE J2 - FIZIKAI SZEMLE VL - 74 PY - 2024 IS - 3 SP - 102 EP - 106 PG - 5 SN - 0015-3257 UR - https://m2.mtmt.hu/api/publication/34742349 ID - 34742349 N1 - "A cikk elkészültét a Nemzeti Kutatási Fejlesztési és Innovációs Hivatal támogatta a K137852, K142179, TKP2021-EGA-02, TKP2021-NVA-02, V4-Japán programok (2019-2.1.7-ERA-NET-2021-00028) révén, valamint a Kulturális és Innovációs Minisztérium a Kvantuminformatika Nemzeti Laboratórium projekt (2022-2.1.1-NL-2022-00004) keretében." LA - Hungarian DB - MTMT ER - TY - JOUR AU - Kucsera, Robin AU - Simon, Ferenc TI - A folyamatok megfordíthatatlansága és a spinechó JF - FIZIKAI SZEMLE J2 - FIZIKAI SZEMLE VL - 73 PY - 2023 IS - 10 SP - 361 EP - 364 PG - 4 SN - 0015-3257 UR - https://m2.mtmt.hu/api/publication/34238621 ID - 34238621 LA - Hungarian DB - MTMT ER - TY - JOUR AU - Lózsa, Rita Bernadett AU - Németh, Eszter AU - Gervai, Judit Zsuzsanna AU - Márkus, Bence Gábor AU - Kollarics, Sándor AU - Gyüre, Zsolt Tamás AU - Tóth, Judit AU - Simon, Ferenc AU - Szüts, Dávid TI - DNA mismatch repair protects the genome from oxygen-induced replicative mutagenesis JF - NUCLEIC ACIDS RESEARCH J2 - NUCLEIC ACIDS RES VL - 51 PY - 2023 IS - 20 SP - 11040 EP - 11055 PG - 16 SN - 0305-1048 DO - 10.1093/nar/gkad775 UR - https://m2.mtmt.hu/api/publication/34192915 ID - 34192915 AB - DNA mismatch repair (MMR) corrects mismatched DNA bases arising from multiple sources including polymerase errors and base damage. By detecting spontaneous mutagenesis using whole genome sequencing of cultured MMR deficient human cell lines, we show that a primary role of MMR is the repair of oxygen-induced mismatches. We found an approximately twofold higher mutation rate in MSH6 deficient DLD-1 cells or MHL1 deficient HCT116 cells exposed to atmospheric conditions as opposed to mild hypoxia, which correlated with oxidant levels measured using electron paramagnetic resonance spectroscopy. The oxygen-induced mutations were dominated by T to C base substitutions and single T deletions found primarily on the lagging strand. A broad sequence context preference, dependence on replication timing and a lack of transcriptional strand bias further suggested that oxygen-induced mutations arise from polymerase errors rather than oxidative base damage. We defined separate low and high oxygen-specific MMR deficiency mutation signatures common to the two cell lines and showed that the effect of oxygen is observable in MMR deficient cancer genomes, where it best correlates with the contribution of mutation signature SBS21. Our results imply that MMR corrects oxygen-induced genomic mismatches introduced by a replicative process in proliferating cells. Graphical Abstract LA - English DB - MTMT ER - TY - JOUR AU - Mukesh, Naina AU - Márkus, Bence Gábor AU - Jegenyés, Nikoletta AU - Bortel, Gábor AU - Morais Bezerra, Sarah AU - Simon, Ferenc AU - Beke, Dávid AU - Gali, Ádám TI - Formation of Paramagnetic Defects in the Synthesis of Silicon Carbide JF - MICROMACHINES J2 - MICROMACHINES-BASEL VL - 14 PY - 2023 IS - 8 PG - 11 SN - 2072-666X DO - 10.3390/mi14081517 UR - https://m2.mtmt.hu/api/publication/34083058 ID - 34083058 AB - Silicon carbide (SiC) is a very promising platform for quantum information processing, as it can host room temperature solid state defect quantum bits. These room temperature quantum bits are realized by paramagnetic silicon vacancy and divacancy defects in SiC that are typically introduced by irradiation techniques. However, irradiation techniques often introduce unwanted defects near the target quantum bit defects that can be detrimental for the operation of quantum bits. Here, we demonstrate that by adding aluminum precursor to the silicon and carbon sources, quantum bit defects are created in the synthesis of SiC without any post treatments. We optimized the synthesis parameters to maximize the paramagnetic defect concentrations—including already established defect quantum bits—monitored by electron spin resonance spectroscopy. LA - English DB - MTMT ER - TY - JOUR AU - Zhang, Yu Jie AU - Simon, Ferenc TI - Fraktálok zenéje – avagy érdekes jelalakok oszcilloszkópon JF - FIZIKAI SZEMLE J2 - FIZIKAI SZEMLE VL - 73 PY - 2023 IS - 4 SP - 137 EP - 140 PG - 4 SN - 0015-3257 UR - https://m2.mtmt.hu/api/publication/34031540 ID - 34031540 N1 - "A cikk elkészültét a Nemzeti Kutatási Fejlesztési és Innovációs Hivatal támogatta a K137852, a TKP2021-EGA-02, továbbá a TKP2021-NVA-02 és a V4-Japán programok által, valamint a Kulturális és Innovációs Minisztérium a Kvantuminformatika Nemzeti Laboratórium projekt (2022-2.1.1-NL-2022-00004) keretében." LA - Hungarian DB - MTMT ER - TY - JOUR AU - Márkus, Bence Gábor AU - Gmitra, M. AU - Dóra, Balázs AU - Csősz, Gábor AU - Fehér, Titusz AU - Szirmai, P. AU - Náfrádi, B. AU - Zólyomi, Viktor AU - Forró, L. AU - Fabian, J. AU - Simon, Ferenc TI - Ultralong 100 ns spin relaxation time in graphite at room temperature JF - NATURE COMMUNICATIONS J2 - NAT COMMUN VL - 14 PY - 2023 IS - 1 PG - 7 SN - 2041-1723 DO - 10.1038/s41467-023-38288-w UR - https://m2.mtmt.hu/api/publication/33831368 ID - 33831368 N1 - Export Date: 08 March 2024 AB - Graphite has been intensively studied, yet its electron spins dynamics remains an unresolved problem even 70 years after the first experiments. The central quantities, the longitudinal ( T 1 ) and transverse ( T 2 ) relaxation times were postulated to be equal, mirroring standard metals, but T 1 has never been measured for graphite. Here, based on a detailed band structure calculation including spin-orbit coupling, we predict an unexpected behavior of the relaxation times. We find, based on saturation ESR measurements, that T 1 is markedly different from T 2 . Spins injected with perpendicular polarization with respect to the graphene plane have an extraordinarily long lifetime of 100 ns at room temperature. This is ten times more than in the best graphene samples. The spin diffusion length across graphite planes is thus expected to be ultralong, on the scale of ~ 70 μ m, suggesting that thin films of graphite — or multilayer AB graphene stacks — can be excellent platforms for spintronics applications compatible with 2D van der Waals technologies. Finally, we provide a qualitative account of the observed spin relaxation based on the anisotropic spin admixture of the Bloch states in graphite obtained from density functional theory calculations. LA - English DB - MTMT ER - TY - JOUR AU - Zhang, Yu Jie AU - Simon, Ferenc TI - A folyamatok megfordíthatatlansága és a Loschmidt-paradoxon JF - FIZIKAI SZEMLE J2 - FIZIKAI SZEMLE VL - 72 PY - 2022 IS - 10 SP - 331 EP - 335 PG - 5 SN - 0015-3257 UR - https://m2.mtmt.hu/api/publication/33334257 ID - 33334257 N1 - "A cikk elkészültét a Nemzeti Kutatási Fejlesztési és Innovációs Hivatal támogatta a K137852, TKP2021-EGA-02, TKP2021-NVA-02 és a V4-Japán programok által, valamint az Innovációs és Technológiai Minisztérium a Kvantuminformatikai Nemzeti Laboratórium projekt keretében." LA - Hungarian DB - MTMT ER - TY - JOUR AU - Zámborszky, F. AU - Gyüre-Garami, B. AU - Jánosi, B. AU - Vajtai, L. AU - Hegyessy, L. AU - Gresits, Iván AU - Simon, Ferenc TI - High-frequency characterization of Fe-based nanocrystalline cores JF - JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS J2 - J MAGN MAGN MATER VL - 564 PY - 2022 PG - 4 SN - 0304-8853 DO - 10.1016/j.jmmm.2022.170027 UR - https://m2.mtmt.hu/api/publication/33287714 ID - 33287714 LA - English DB - MTMT ER - TY - JOUR AU - Bojtor, András AU - Kollarics, Sándor AU - Márkus, Bence Gábor AU - Sienkiewicz, A. AU - Kollár, M. AU - Forró, L. AU - Simon, Ferenc TI - Ultralong Charge Carrier Recombination Time in Methylammonium Lead Halide Perovskites JF - ACS PHOTONICS J2 - ACS PHOTONICS VL - 9 PY - 2022 IS - 10 SP - 3341 EP - 3350 PG - 10 SN - 2330-4022 DO - 10.1021/acsphotonics.2c00687 UR - https://m2.mtmt.hu/api/publication/33068961 ID - 33068961 N1 - WOS:000838383900002 AB - Due to their exceptional photovoltaic properties, metal halide perovskites (MHPs) are extensively studied for their potential applications in solar cells. In recent years, the power conversion efficiencies of MHPs-based solar cells rapidly increased from the initial few % toward more than 25% for single-junction devices. Therefore, also taking into account their low costs and ease of manufacturing, MHPs-based solar cells have become the fastest-advancing photovoltaic technology. In this regard, much of the recent work has been dominated by absorber materials based on methylammonium MHPs, such as MAPbX3, where MA = CH3NH3 and X = Cl, Br, and I. Here, we present the results of contactless time-resolved photoconductivity measurements in an exceptionally wide range of temperatures of 4 to 290 K that were performed for the various crystalline forms of the three parent MAPbX3, that is, MAPbCl3, MAPbBr3, and MAPbI3. This approach was made possible by the use of a high quality factor (Q) microwave resonator, which cooperated with a commercially available microwave bridge equipped with an automatic frequency control (AFC) and a helium gas-flow cryostat. The structural phase transitions from orthorhombic to tetragonal are found to drastically affect the transient photoconductivity signal, and we also observe ultralong charge carrier recombination times approaching 70 its at low temperatures. The difference caused by morphology on the photophysical properties is supported by a marked difference between rapidly cooled (quenched) and slowly cooled samples. The sensitive technique also allowed to observe differences between samples with different morphologies and crystallite sizes. LA - English DB - MTMT ER -