TY - JOUR AU - Tóth, Boglárka AU - Farkas, Dániel Gergely AU - Amelin, K. AU - Rõõm, T. AU - Nagel, U. AU - Udvardi, László AU - Szunyogh, László AU - Rózsa, Levente AU - Ito, T. AU - Bordács, Sándor TI - Terahertz spin-wave excitations in the transverse conical phase of BiFeO3 JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 109 PY - 2024 IS - 14 PG - 10 SN - 2469-9950 DO - 10.1103/PhysRevB.109.144424 UR - https://m2.mtmt.hu/api/publication/34823661 ID - 34823661 N1 - Department of Physics, Institute of Physics, Budapest University of Technology and Economics, Muegyetem rakpart 3, Budapest, H-1111, Hungary National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn, 12618, Estonia Department of Theoretical Physics, Institute of Physics, Budapest University of Technology and Economics, Muegyetem rakpart 3, Budapest, H-1111, Hungary HUN-REN-BME Condensed Matter Physics Research Group, Budapest University of Technology and Economics, Muegyetem rakpart 3, Budapest, H-1111, Hungary Department of Theoretical Solid State Physics, Institute for Solid State Physics and Optics, HUN-REN Wigner Research Centre for Physics, Budapest, H-1525, Hungary National Institute of Advanced Industrial Science and Technology, Ibaraki, Tsukuba, 305-8562, Japan Experimental Physics v, Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg, D-86135, Germany Export Date: 10 May 2024 Funding details: Eesti Teadusagentuur, ETAg, PRG736 Funding details: NKM2022-27/2023, NKM 2018-47, NKM 2021-24 Funding details: 2022-2.1.1-NL-2022-00004 Funding details: Nemzeti Kutatási Fejlesztési és Innovációs Hivatal, NKFIH, K 131938, FK 135003, K 142652, FK 142601 Funding details: European Regional Development Fund, ERDF, TK134 Funding details: Magyar Tudományos Akadémia, MTA, BO/00178/23/11 Funding text 1: We thank R.S. Fishman for discussions. The authors acknowledge the support of the bilateral program of the Estonian and Hungarian Academies of Sciences under Contracts No. NKM 2018-47, No. NKM 2021-24, and No. NKM2022-27/2023. We acknowledge support from Estonian Research Council Grant No. PRG736 and European Regional Development Fund Project No. TK134. This research was supported by the Ministry of Culture and Innovation and the National Research, Development and Innovation Office within the Quantum Information National Laboratory of Hungary (Grant No. 2022-2.1.1-NL-2022-00004). This work was supported by the Hungarian National Research, Development and Innovation Office (NKFIH Grants No. FK 135003, No. K 131938, No. K 142652, and No. FK 142601), as well as by the Hungarian Academy of Sciences via a J\\u00E1nos Bolyai Research Grant (Grant No. BO/00178/23/11). LA - English DB - MTMT ER - TY - JOUR AU - Nagyfalusi, Balázs AU - Udvardi, László AU - Szunyogh, László AU - Rózsa, Levente TI - Chemical potential of magnetic skyrmion quasiparticles in heavy-metal/iron bilayers JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 109 PY - 2024 IS - 9 PG - 9 SN - 2469-9950 DO - 10.1103/PhysRevB.109.094418 UR - https://m2.mtmt.hu/api/publication/34749006 ID - 34749006 LA - English DB - MTMT ER - TY - JOUR AU - Martínez-Carracedo, G. AU - Oroszlány, László AU - García-Fuente, A. AU - Nyári, Bendegúz Tamás AU - Udvardi, László AU - Szunyogh, László AU - Ferrer, J. TI - Relativistic magnetic interactions from nonorthogonal basis sets JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 108 PY - 2023 IS - 21 PG - 18 SN - 2469-9950 DO - 10.1103/PhysRevB.108.214418 UR - https://m2.mtmt.hu/api/publication/34470105 ID - 34470105 LA - English DB - MTMT ER - TY - JOUR AU - Udvardi, László AU - László, István TI - Topological charges of fullerenes JF - JOURNAL OF MATHEMATICAL CHEMISTRY J2 - J MATH CHEM VL - 61 PY - 2023 IS - 2 SP - 335 EP - 342 PG - 8 SN - 0259-9791 DO - 10.1007/s10910-022-01354-7 UR - https://m2.mtmt.hu/api/publication/32896293 ID - 32896293 N1 - Funding Agency and Grant Number: Budapest University of Technology and Economics Funding text: Open access funding provided by Budapest University of Technology and Economics. AB - We defined the topological charge and bump number for fullerenes. All even fullerene isomers from C-20 up to C-70 were constructed. After optimizing the geometry of the molecules the relation between the topological charge, the bump number and the atomization energy were analysed. LA - English DB - MTMT ER - TY - JOUR AU - Nagyfalusi, Balázs AU - Udvardi, László AU - Szunyogh, László TI - Magnetic ground state of supported monatomic Fe chains from first principles JF - JOURNAL OF PHYSICS-CONDENSED MATTER J2 - J PHYS CONDENS MAT VL - 34 PY - 2022 IS - 39 PG - 10 SN - 0953-8984 DO - 10.1088/1361-648X/ac8260 UR - https://m2.mtmt.hu/api/publication/33041619 ID - 33041619 AB - A new computational scheme is presented based on a combination of the conjugate gradient and the Newton-Raphson method to self-consistently minimize the energy within local spin-density functional theory, thus to identify the ground state magnetic order of a finite cluster of atoms. The applicability of the new ab initio optimization method is demonstrated for Fe chains deposited on different metallic substrates. The optimized magnetic ground states of the Fe chains on Rh(111) are analyzed in details and a good comparison is found with those obtained from an extended Heisenberg model containing first principles based interaction parameters. Moreover, the effect of the different bilinear spin-spin interactions in the formation of the magnetic ground states is monitored. In case of Fe chains on Nb(110) spin-spiral configurations with opposite rotational sense are found as compared to previous spin-model results which hints on the importance of higher order chiral interactions. The wavelength of the spin-spiral states of Fe chains on Re(0001) was obtained in good agreement with scanning tunneling microscopy experiments. LA - English DB - MTMT ER - TY - JOUR AU - Nagyfalusi, Balázs AU - Udvardi, László AU - Szunyogh, László AU - Rózsa, Levente TI - Spin reorientation transition in an ultrathin Fe film on W(110) induced by Dzyaloshinsky-Moriya interactions JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 102 PY - 2020 IS - 13 PG - 6 SN - 2469-9950 DO - 10.1103/PhysRevB.102.134413 UR - https://m2.mtmt.hu/api/publication/31645795 ID - 31645795 AB - Controlling the preferred direction of the magnetic moments is essential for the design of spintronic devices based on ultrathin films and heterostructures. As the film thickness or the temperature is increased, the easy anisotropy axis is typically reoriented from an out-of-plane direction preferred by surface and interface energy contributions to an in-plane alignment favored by the volume anisotropy terms. We study the temperature-driven spin reorientation transition in two atomic layers of Fe on W(110) using well-tempered metadynamics simulations based on a spin model parametrized by ab initio calculations and find that the transition only takes place in the presence of the Dzyaloshinsky-Moriya interaction (DMI). This demonstrates that the chiral DMI does not only differentiate between noncollinear spin structures of different rotational senses, but it also influences the magnetic orientation of collinear magnetic configurations. LA - English DB - MTMT ER - TY - JOUR AU - Nagyfalusi, Balázs AU - Udvardi, László AU - Szunyogh, László TI - Metadynamics study of the temperature dependence of magnetic anisotropy and spin-reorientation transitions in ultrathin films JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 100 PY - 2019 IS - 17 PG - 9 SN - 2469-9950 DO - 10.1103/PhysRevB.100.174429 UR - https://m2.mtmt.hu/api/publication/31015490 ID - 31015490 AB - We employ metadynamics simulations to calculate the free-energy landscape of thin ferromagnetic films and perform a systematic study of the temperature dependence of magnetic anisotropy and of the spin-reorientation transitions. By using a simple spin model we recover the well-known power-law behavior of the magnetic anisotropy energy against magnetization and present a rather detailed analysis of the spin-reorientation transitions in ultrathin films. Based on tensorial exchange interactions and anisotropy parameters derived from first-principles calculations, we perform simulations for Fe double layers deposited on Au(001) and W(110). In the case of Fe2W(110) our simulations display an out-of-plane to in-plane spin-reorientation transition in agreement with experiments. LA - English DB - MTMT ER - TY - JOUR AU - Lászlóffy, András AU - Rózsa, Levente AU - Palotás, Krisztián AU - Udvardi, László AU - Szunyogh, László TI - Magnetic structure of monatomic Fe chains on Re(0001): Emergence of chiral multispin interactions JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 99 PY - 2019 IS - 18 PG - 13 SN - 2469-9950 DO - 10.1103/PhysRevB.99.184430 UR - https://m2.mtmt.hu/api/publication/30709889 ID - 30709889 LA - English DB - MTMT ER - TY - JOUR AU - Oroszlány, László AU - Jaime, Ferrer AU - Deák, András AU - Udvardi, László AU - Szunyogh, László TI - Exchange interactions from a nonorthogonal basis set: From bulk ferromagnets to the magnetism in low-dimensional graphene systems JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 99 PY - 2019 IS - 22 PG - 12 SN - 2469-9950 DO - 10.1103/PhysRevB.99.224412 UR - https://m2.mtmt.hu/api/publication/30708358 ID - 30708358 LA - English DB - MTMT ER - TY - JOUR AU - Hsu, P-J AU - Rózsa, Levente AU - Finco, A AU - Schmidt, L AU - Palotás, Krisztián AU - Vedmedenko, E AU - Udvardi, László AU - Szunyogh, László AU - Kubetzka, A AU - Von Bergmann, K AU - Wiesendanger, R TI - Inducing skyrmions in ultrathin Fe films by hydrogen exposure JF - NATURE COMMUNICATIONS J2 - NAT COMMUN VL - 9 PY - 2018 IS - 1 PG - 7 SN - 2041-1723 DO - 10.1038/s41467-018-04015-z UR - https://m2.mtmt.hu/api/publication/3368135 ID - 3368135 LA - English DB - MTMT ER -