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Details of project

  
Identifier
46267
Type K
Principal investigator Szunyogh, László
Title in Hungarian Hibrid mágneses szerkezetek
Title in English Hybrid magnetic structures
Panel Physics 1
Department or equivalent Department of Theoretical Physics (Budapest University of Technology and Economics)
Participants Udvardi, László
Újfalussy, Balázs
Zaránd, Gergely Attila
Starting date 2004-01-01
Closing date 2008-06-30
Funding (in million HUF) 9.970
FTE (full time equivalent) 0.00
state closed project





 

Final report

  
Results in Hungarian
'Hibrid mágneses szerkezetek' c. pályázatunkban két témakörben: (i) a mágneses nanostruktúrák ab initio szintű vizsgálatában és (ii) a mágneses félvezetők valamint a kvantumszennyezők tanulmányozásában végeztünk intenzív elméleti kutatásokat: (i) Atomcsoportok és ultravékony filmek mágneses szerkezetét határoztuk meg, rávilágítva a Dzyaloshinskii-Moriya kölcsönhatás jelentőségére. A nagysűrűségű mágneses adattárolás szempontjából meghatározó mágneses anizotrópia kontroll-mechanizmusait vizsgáltuk vékonyrétegekben. Kidolgoztuk a mágneses anizotrópia energia hőmérsékletfüggésének ab initio elméletét. Részletesen tanulmányoztuk az áram által hajtott spinátfordulás jelenségét és a magneto-optikai Kerr effektust; (ii) Rámutattunk a nem-kollineáris állapotok kialakulására GaMnAs híg mágneses félvezetőben és skálaelméletet dolgoztunk ki a magnetotranszport leírására. Új mechanizmust javasoltunk egy Kondo szennyező felületi mágneses anizotrópiájára. Részletesen vizsgáltuk a spin szennyezések elektron koherenciára gyakorolt hatását, a spinek relaxációját és a kvantum dot rendszerek dinamikáját. Pályázatunk elsősorban az alapkutatásba sorolható, bár a nanomágnesség és spintronika területén több alkalmazás orientált eredményünk született (pl. komplex vékonyrétegek mágneses anizotrópiája, áram által hajtott spinátfordulás, magnetotranszport mágneses félvezetőkben).
Results in English
In our research project entitled 'Hybrid magnetic structures' we performed intensive theoretical research on (i) magnetic nanostructures and (ii) on magnetic semiconductors and quantum impurities: (i) By highlighting the role of the Dzyaloshinskii-Moriya interactions, we determined the magnetic structure of small atomic clusters and ultrathin films. We carefully investigated the control of magnetic anisotropy that is of primary importance for high-density magnetic recording. We developed a first principles theory for the temperature dependence of the magnetic anisotropy energy. We also studied the phenomena of current driven magnetization switching and magneto-optical Kerr effect; (ii) We pointed out the formation of non-collinear states in GaMnAs magnetic semiconductor and developed a scaling theory for the description of magnetotransport. We proposed a novel mechanism for the surface magnetic anisotropy of Kondo impurities. We performed detailed studies on the effect of spin-impurities to electron coherence, on the relaxation spins and the dynamics of quantum dot systems. Although the results of our project mainly concern fundamental research, some of them, such as the magnetic anisotropy of ultrathin films, current induced spin-switching, magnetotransport in magnetic semiconductors, might be useful for applications in nanomagnetism and spintronics.
Full text https://www.otka-palyazat.hu/download.php?type=zarobeszamolo&projektid=46267
Decision
Yes





 

List of publications

  
S. Gallego S, L. Szunyogh, P. Weinberger, and M.C. Munoz: Origin of the magnetic reorientation transition of Fe/Cu3Au(001), Phys. Rev. B 69, 224408, 2004
P. Weinberger, A. Vernes, B.L. Györffy, and L. Szunyogh: Noncollinear magnetic structures: A possible cause for current-induced switching, Phys. Rev. B 70, 094401, 2004
B. Lazarovits, B. Újfalussy, L. Szunyogh, G.M. Stocks, and P. Weinberger: Ab initio study of of canted magnetism of finite metallic chains at surfaces canted magnetism of finite metallic chains at surfaces, J. Phys.: Condens. Matter 16, S5833-S5840, 2004
B. Újfalussy, B. Lazarovits, L. Szunyogh, G.M. Stocks, and P. Weinberger: Ab initio spin dynamics applied to nanoparticles: canted magnetism of a finite Co chain along a Pt(111) surface step edge canted magnetism of a finite Co chain along a Pt(111) surface step edge, Phys. Rev. B 70, 100404(R), 2004
K. Palotás, B Lazarovits, L. Szunyogh, and P. Weinberger: Ab initio study of the electric transport in gold nanocontacts containing single impurities containing single impurities, Phys. Rev. B 70, 134421, 2004
I. Reichl, R. Hammerling, A. Vernes, P. Weinberger, C. Sommers, and L. Szunyogh: Ab initio determination of Kerr angles in Cu4Ni8CunNi9/Cu(100) (n = 2-10), Phys. Rev. B 70, 214417, 2004
J.B. Staunton, S. Ostanin, S.S.A. Razee, B.L. Györffy, L. Szunyogh, B. Ginatempo, and E. Bruno: Temperature dependent magnetic anisotropy in metallic magnets from an ab-initio electronic structure theory: L10-ordered FePt, Phys. Rev. Lett. 93: 257204, 2004
L. Borda, G. Zaránd, and P. Simon: Dissipation-induced quantum phase transition in a quantum box, Phys. Rev. B 72, 155311, 2005
G. Zaránd, C. P. Moca, and B. Jankó: Scaling Theory of Magnetoresistance in Disordered Local Moment Ferromagnets, Phys. Rev. Lett. 94, 247202, 2005
G. A. Fiete, G. Zaránd, B. Jankó, P. Redlinski, and C. Pascu Moca: Positional disorder, spin-orbit coupling, and frustration in Ga(1-x)Mn(x)As, Phys. Rev. B 71, 115202, 2005
E. Novais, A. H. Castro Neto, L. Borda, I. Affleck, and G. Zaránd: Frustration of decoherence in open quantum systems, Phys. Rev. B 72, 014417, 2005
P. Mehta, N. Andrei, P. Coleman, L. Borda, and G. Zaránd: Regular and singular Fermi-liquid fixed points in quantum impurity models, Phys. Rev. B 72, 014430, 2005
A. Vernes, P. Weinberger, and L. Szunyogh: Current-induced switching in Py/Cu/Py spin valves, Phys. Rev. B 72, 012401, 2005
I. Reichl, A. Vernes, P. Weinberger, L. Szunyogh, C. Sommers: Reorientation transition in Fe(n)/Au(100), Phys. Rev. B 71, 214416, 2005
B. Lazarovits, P. Simon, G. Zaránd, and L. Szunyogh: Exotic Kondo effect from magnetic trimers, Phys. Rev. Lett. 95, 077202, 2005
B. Lazarovits, B. Újfalussy, L. Szunyogh, B. L. Györffy, and P. Weinberger: Magnetic properties of quantum corrals from 'first principles' calculations, J. Phys.: Condens. Matter 17, S1037-S1048, 2005
G. Zaránd: Existence of a two-channel Kondo regime for tunneling impurities with resonant scattering, Phys. Rev. B 72, 245103, 2005
R. Hammerling, J. Zabloudil, L. Szunyogh, and P. Weinberger: Solution of the Poisson equation for infinite and semi-infinite systems including near eld corrections for charge densities of arbitrary shape, Philosophical Magazine 86, 25-48, 2006
B. Lazarovits, L. Szunyogh, P. Weinberger: Spin-polarized surface states close to adatoms on Cu(111), Phys. Rev. B 73, 045430, 2006
I. Reichl, J. Zabloudil, R. Hammerling, A. Vernes, L. Szunyogh, and P. Weinberger: Magneto-optical Kerr effect in perpendicularly magnetized (Co2Pt6)n/Pt(111) superstructures, Phys. Rev. B 73, 054402, 2006
L. Szunyogh, G. Zaránd, S. Gallego, M.C. Munoz, and B.L. Györffy: Effect of spin-orbit coupling of a magnetic impurity in the vicinity of a surface, Phys. Rev. Lett. 96, 067204, 2006
J. Zabloudil, R. Hammerling, L. Szunyogh, and P. Weinberger: Bulk and surface properties of metals by full-charge-density screened Korringa-Kohn-Rostoker calculations, Phys. Rev. B 73, 115410, 2006
L. Udvardi, S. Khmelevskyi, L. Szunyogh, P. Mohn, and P. Weinberger: Helimagnetism and competition of exchange interactions in novel bulk GMR alloys based on MnAu2, Phys. Rev. B 73, 104446, 2006
J.B. Staunton, L. Szunyogh, Á. Buruzs, B.L. Györffy, S. Ostanin, and L. Udvardi: Temperature dependence of magnetic anisotropy: An ab initio approach, Phys. Rev. B 74, 144411, 2006
K. Palotás, B. Lazarovits, P. Weinberger, and L. Szunyogh: Electric Properties of Nanostructures, Handbook of Theoretical and Computational Nanotechnology, eds. Michael Rieth and Wolfram Schommers. American Scientific Publishers, Los Angeles, Vol 10, Ch. 6, 363-408, 2006
Farid El Gabaly, Silvia Gallego, Carmen Munoz, Laszlo Szunyogh, Peter Weinberger, Christof Klein, Andreas K. Schmid, Kevin F. McCarty, and Juan de la Figuera: Imaging Spin Reorientation Transitions in Consecutive Atomic Co layers on Ru(0001), Phys. Rev. Lett. 96, 147202, 2006
G. Zaránd, CH Chung, P. Simon, and M. Vojta: Quantum criticality in a double-quantum-dot system, Phys. Rev. Lett. 97, 166802, 2006
P. San-Jose, G. Zaránd, A. Shnirman, and G. Schön: Geometrical spin dephasing in quantum dots, Phys. Rev. Lett. 97, 076803, 2006
Á. Rapp and G. Zaránd: Dynamical correlations and quantum phase transition in the quantum Potts model, Phys. Rev. B 74, 014433, 2006
R.K. Kaul, G. Zaránd, S. Chandrasekharan, D. Ullmo, and H.U. Baranger: Spectroscopy of the Kondo problem in a box, Phys. Rev. Lett. 96, 176802, 2006
J. Rech, P. Coleman, G. Zaránd, and O. Parcollet: Schwinger boson approach to the fully screened Kondo model, Phys. Rev. Lett. 96, 016601, 2006
G. Zaránd: Quantum Impurity Problems, MTA doktora értekezés, 2005
G. Zaránd: Orbital fluctuations and strong correlations in quantum dots, Philosophical Magazine 86, 2043-2072, 2006
G. Zaránd, L. Borda, J. von Delft, and N. Andrei: Theory of Inelastic Scattering from Magnetic Impurities, Phys. Rev. Lett. 93, 107204, 2004
G. A. Fiete, G. Zaránd, K. Damle, C. Pascu Moca: Disorder, spin-orbit, and interaction effects in dilute Ga(1-x)Mn(x)As, Phys. Rev. B 72, 045212, 2005
P. San-Jose, B. Scharfenberger, G. Schön, A. Shnirman and G. Zaránd: Geometric phases in semiconductor spin qubits: Manipulations and decoherence, Phys. Rev. B 77, 045305, 2008
A.I. Tóth, L. Borda, J. von Delft, G. Zaránd: Dynamical conductance in the two-channel Kondo regime of a double dot system, Phys. Rev. B 76, 155318, 2007
C. Pascu Moca, E. Demler, B. Janko, and G. Zaránd: Spin-resolved spectra of Shiba multiplets from Mn impurities in MgB2, Phys. Rev. B 77, 174516, 2008
Á. Rapp, G. Zaránd, C. Honerkamp, and W. Hofstetter: Color Superfluidity and "Baryon" Formation in Ultracold Fermions, Phys. Rev. Lett. 98, 160405, 2007
Á. Rapp, W. Hofstetter, and G. Zaránd: Trionic phase of ultracold fermions in an optical lattice: A variational study, Phys. Rev. B 77, 144520, 2008
G.M. Stocks, M. Eisenbach, B. Újfalussy, B. Lazarovits, L. Szunyogh, and P. Weinberger: On calculating the magnetic state of nanostructures, Progress in Materials Science 52, 371-387, 2007
C. Etz, B. Lazarovits, J. Zabloudil, R. Hammerling, B. Újfalussy, L. Szunyogh, G. M. Stocks, and P. Weinberger: Magnetic properties of FeCo nanoclusters on Cu(100): Ab initio calculations, Phys. Rev. B 75, 245432, 2007
O. Újsághy, L. Szunyogh, and A. Zawadowski: Revised theory of the magnetic surface anisotropy of impurities in metallic mesoscopic samples, Phys. Rev. B 75, 064425, 2007
A. Antal, L. Udvardi, B. Újfalussy, B. Lazarovits, L. Szunyogh, and P. Weinberger: Magnetic properties of a Cr trimer on Au(111) surface, Journal of Magnetism and Magnetic Materials 316, 118-121, 2007
Á. Buruzs, L. Szunyogh, L. Udvardi, P. Weinberger, and J.B. Staunton: Temperature dependent magneto-crystalline anisotropy of thin films: A relativistic disordered local moment approach, Journal of Magnetism and Magnetic Materials 316, e371-e373, 2007
Á. Buruzs, P. Weinberger, L. Szunyogh, L. Udvardi, P. I. Chleboun, A. M. Fischer, and J.B. Staunton: Ab initio theory of temperature dependence of magnetic anisotropy in layered systems: Applications to thin Co films on Cu(100), Phys. Rev. B 76, 064417, 2007
L. Udvardi, A. Antal, L. Szunyogh, Á. Buruzs and P. Weinberger: Magnetic pattern formation on the nanoscale due to relativistic exchange interactions, Physica B 403, 402-404, 2008
C. Etz, A. Vernes, L. Szunyogh, and P. Weinberger: Ab initio magneto-optical properties of bcc Ni/Ni(100), Phys. Rev. B 77, 064420, 2008



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