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C.27. Ropo * M, Kokko * K, Punkkinen * MPJ, Hogmark * S, Kollár J, Johansson * B, and Vitos L; Theoretical evidence of the compositional threshold behavior of FeCr surfaces; Phys Rev B; Rapid Communication; accepted for publication C.28. Kádas K, Vitos L, Ahuja * R, Johansson * B, Kollár J; Temperature dependent elastic properties of α-beryllium from first principles theory; Phys Rev B; accepted for publication Article in Hungarian C.29. Kollár J; Fémek felületi struktúrájának kvantummechanikája (Quantum mechanics of metallic surface structures, in Hungarian); Fizikai Szemle; 57, 42-46, 2007 Books and book chapters C.30. Vitos L; Computational quantum mechanics for materials engineers. The EMTO method and applications; Springer-Verlag, London, Series: Engineering Materials and Processes, 2007 C.31. Vitos L, Johansson * B; Mechanical properties of random alloys from quantum mechanical simulations; In: Applied Parallel Computing. State of the Art in Scientific Computing, Lecture Notes in Computer Science; Eds.: Heidelberg, B. Kagström et al. Springer-Verlag Berlin, Vol 4699; pp. 510-519, 2007 18
D. NON-EQUILIBRIUM ALLOYS I. Vincze, J. Balogh, L. Bujdosó, D. Kaptás, T. Kemény, L.F. Kiss Perpendicular Anisotropy in Fe-Ag Multilayers. — The direction of the spontaneous magnetization was observed in our previous studies to change from in plane to out of plane below 1 nm Fe layer thickness in Fe-Ag multilayers. This transition is studied in more details on a set of samples with the following structure: [Ag(2.6 nm)/ 57 Fe(x nm)] 10 (0.2 ≤ x ≤ 1). The samples were prepared on room temperature Si(111) substrates by vacuum evaporation. For transmission Mössbauer spectroscopy measurements they were capped with a thick capping layer (55 nm Ag and 100 nm B) and the deposited layers were removed from the substrate by using scotch tape. The stress arising because of the application of a thick capping layer and the removal of the samples from the substrate was shown to have negligible effect on the spontaneous magnetization by comparing the results to conversion electron Mössbauer spectroscopy measurements of samples on the Si substrate with a thin, 5 nm Ag, capping layer. The samples show superparamagnetic behavior in the whole Fe thickness range. This is indicated by the deviation of the field cooled (FC) and zero field cooled (ZFC) magnetization curves measured by a SQUID magnetometer, as shown in Fig. 1 for a few representative samples. The blocking temperature, as defined by the temperature of the maximum in the ZFC magnetization, is 34 K for x=0.2 and rapidly increases with increasing x until x=0.5. The broadening of the distribution in the size of the superparamagnetic grains with increasing x can also be inferred from the ZFC curves. Samples with x ≥ 0.6 are also superparamagnetic, as it is indicated by in-field Mössbauer measurements (not shown here), but for M (emu/g) 0 0 50 100 150 200 250 300 350 T (K) Fig. 1. Temperature dependence of the magnetization of the x=0.4 (diamonds), 0.5 (triangles), and 0.7 (squares) [Ag(2.6 nm)/ 57 Fe(x nm)] 10 samples measured in 10 Oe magnetic field after cooling the sample in zero (full symbols) and 10 Oe (open symbols) applied field. Note the smaller magnetization scale for x=0.4 and 0.5. the majority of the Fe atoms the blocking temperature (T B ) is well above room temperature. The low temperature anomaly of the FC-ZFC curves of these samples (for x=0.7 see Fig. 1) can be attributed to an about 10-20% of the Fe atoms forming smaller grains with T B below room temperature. The direction of the spontaneous magnetization was studied by Mössbauer spectroscopy. The intensity of the 2 nd and 5 th lines (I 25 ) of a magnetic sextet with respect to that of the 3 rd and 5 th lines is determined by the angle (θ) between the direction of the local magnetization and of the γ-ray, I 25 =4 sin 2 θ / (1+cos 2 θ) During a perpendicular to in-plane transition of the magnetization I 25 changes from 4 to zero. In the case of a hyperfine field distribution an average value of I 25 can be given by supposing a uniform direction of all the magnetic moments. The I 25 amplitudes determined in a broad temperature range below T B for several samples are shown in Fig. 2. A significant change of the magnetization 220 200 180 160 14 12 10 8 6 4 2 M (emu/g) 19
Page 1 and 2: ANNUAL REPORT 2007 RESEARCH INSTITU
Page 3 and 4: Dear Reader, It is my pleasure to h
Page 5 and 6: Key figures Permanent staff of the
Page 8 and 9: A. STRONGLY CORRELATED SYSTEMS J. S
Page 10 and 11: presented detailed study should hel
Page 12 and 13: B. COMPLEX SYSTEMS F. Iglói, R. Ju
Page 14 and 15: B.3. B.4. B.5. B.6. B.7. B.8. B.9.
Page 16 and 17: the α2 reconstruction increases on
Page 18 and 19: C.2. C.3. Kádas K, Vitos L, Johans
Page 22 and 23: I 25 4 3 Fig. 2. Average intensity
Page 24 and 25: See also H.6. and nanostructured Pd
Page 26 and 27: Ab initio structure solution. — I
Page 28 and 29: ESA PECS 98021 Phase field modeling
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Page 46 and 47: I.13 Kane * SN, Khinchi * SS, Gercs
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Page 52 and 53: Macromolecular Compounds (Visokomol
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Bilateral Austro-Hungarian Cooperat
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P. FEMTOSECOND LASERS R. Szipőcs,
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Grants and international cooperatio
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E-Mail: Kárpát Ferencz optilab@t-
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y optical microscopy. While in Y 2
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Publications: Articles R.1. Földv
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S. CHARACTERIZATION AND POINT DEFEC
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groups of the Li 2 B 4 O 7 lattice.
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S.10. Lengyel K, Kovács L, Péter
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entanglement one has to find method
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T.7. T.8. T.9. Asbóth JK, Domokos
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EDUCATION Graduate and postgraduate
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Laboratory practice and seminars
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G. Dravecz (ELTE and Université de
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TABLE of CONTENTS PREFACE 1 KEY FIG
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