Electronic structure of face-centered-tetragonal iron in ferromagnetic iron-copper multilayers

Physical Review B - Condensed Matter and Materials Physics

Volumn 59, Issue 3, 1999, Pages 2352-2362

  Lloyd, S J ^a   Dunin Borkowski, R E ^a  

^a UNIVERSITY OF CAMBRIDGE   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0006182213     PISSN: 10980121     EISSN: 1550235X     Source Type: Journal    
DOI: 10.1103/PhysRevB.59.2352     Document Type: Article

References (65)

1. F. Capasso, Science 235, 172 (1987).
2. R. W. Cahn, Nature (London) 324, 108 (1986).
3. Ultrathin Magnetic Structures, edited by J. A. C. Bland and B. Heinrich (Springer-Verlag, Berlin, 1994), Vols. I and II.
4. E. E. Fullerton, I. K. Schuller, F. T. Parker, K. A. Svinarich, G. L. Eesley, R. Bhadra, and M. Grimsditch, J. Appl. Phys. 73, 7370 (1993).
5. G. A. Prinz, J. Magn. Magn. Mater. 100, 469 (1991).
6. B. M. Clemens and G. L. Eesley, Phys. Rev. Lett. 61, 2356 (1988).
7. W. F. Egelhoff, in Ultrathin Magnetic Structures (Ref. 3).
8. On the formation of a coherent multilayer from what are conventionally understood as cubic components, the symmetry of the structure within the individual layers is reduced to tetragonal as a result of atomic spacing changes associated with the constraint of coherent growth. While the conventional Bravais lattice of the material within each layer is body-centered-tetragonal, in order to preserve the simple relationship with the original cubic lattice a face-centered-tetragonal cell with c defined along the layer normal is referred to here.
9. F. Yoshizaki, N. Tanaka, and K. Mihama, J. Electron Microsc. 39, 459 (1990).
10. V. L. Moruzzi, P. M. Marcus, and J. Kubler, Phys. Rev. B 39, 6957 (1989).
11. G. J. Johanson, M. B. McGirr, and D. A. Wheeler, Phys. Rev. B 1, 3208 (1970).
12. U. Gonser, K. Krischel, and S. Nasu, J. Magn. Magn. Mater. 15–18, 1145 (1980).
13. D. Li, M. Freitag, J. Pearson, Z. Q. Qiu, and S. D. Bader, J. Appl. Phys. 76, 6425 (1994).
14. B. Heinrich and J. F. Cochran, Adv. Phys. 42, 523 (1993).
15. The sputtering conditions were to initially chosen favor nucleation processes to form a continuous Cu buffer (a low sputtering pressure of ∼1 Pa and a low deposition rate of ∼0.01 nm (Formula presented) were used). The multilayers were then grown at a higher sputtering pressure (∼4.5 Pa) and a higher deposition rate (∼0.1 nm (Formula presented)), with the temperature reduced during deposition from ∼470 to ∼400 K. See R. E. Somekh and C. S. Baxter, J. Cryst. Growth 76, 119 (1986).
16. S. J. Lloyd, R. E. Somekh and W. M. Stobbs, in Metastable Phases and Microstructures, edited by R. Bormann, G. Mazzone, R. S. Averback, R. D. Shull, and R. F. Ziolo, MRS Symposia Proceedings No. 400 (Materials Research Society, Pittsburgh, 1996), p. 317.
17. E. E. Fullerton, I. K. Schuller, H. Vanderstraeten, and Y. Bruynseraede, Phys. Rev. B 45, 9292 (1992).
18. Elastic, Piezoelectric, Piezooptic, Electrooptic, Constants, and Nonlinear Dielectric Susceptibilities of Crystals, edited by K. H. Hellwege and O. Madelung, Landolt-Börnstein, New Series, Group III, Vol. 2 (Springer-Verlag, Berlin, 1969).
19. R. A. Johnson, Phys. Rev. 145, 423 (1966).
20. S. H. Lu, J. Quinn, D. Tian, and F. Jona, Surf. Sci. 209, 364 (1989).
21. S. J. Lloyd, R. E. Somekh, and W. M. Stobbs, in Structure and Properties of Multilayered Thin Films, edited by T. D. Nguyen, B. M. Lairson, B. M. Clemens, K. Sato, MRS Symposia Proceedings No. 382 and S-C. Shin (Materials Research Society, Pittsburgh, 1995), p. 155
22. C. S. Baxter and W. M. Stobbs, Ultramicroscopy 16, 213 (1985).
23. In high-energy electron diffraction, only the Coulomb potential needs to be considered since exchange and correlation effects are negligible (Refs. 24 and 25).
24. D. K. Saldin and J. C. H. Spence, Ultramicroscopy 55, 397 (1994).
25. P. Rez, Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. 34, 48 (1978).
26. See, e.g., P. B. Hirsch, A. Howie, R. Nicholson, D. W. Pashley, and M. J. Whelan, Electron Microscopy of Thin Crystals, 2nd ed. (Krieger, Florida, 1977).
27. F. M. Ross and W. M. Stobbs, Philos. Mag. A 63, 1 (1991);
28. Philos. Mag. AF. M. RossW. M. Stobbs63, 37 (1991).
29. R. F. Egerton, Electron Energy-Loss Spectroscopy in the Electron Microscope, 2nd ed. (Plenum, New York, 1996).
30. R. E. Dunin-Borkowski, C. B. Boothroyd, S. J. Lloyd, and W. M. Stobbs, J. Microsc. 180, 263 (1995).
31. W. H. Press, B. P. Flannery, S. A. Teukolsky, and W. T. Vetterling, Numerical Recipes (Cambridge University Press, Cambridge, 1989).
32. R. E. Dunin-Borkowski (unpublished).
33. P. A. Doyle and P. S. Turner, Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. 24, 390 (1968).
34. D. Rez, P. Rez, and I. Grant, Acta Crystallogr., Sect. A: Found. Crystallogr. 50, 481 (1994).
35. Only after considering the possible contributions to the observed values of (Formula presented) is it possible to assess which, if either, of the two sets of scattering factors are the more appropriate. If the other parameters affecting the value of (Formula presented) can be determined independently, then an analysis of the Fresnel contrast may in principle be used to determine the true scattering factors, and hence to infer the electron distribution within the multilayer.
36. The white lines result from the excitation of p electrons into d-band empty states, and are sensitive to crystal structure, lattice spacing, local charge transfer, and magnetic moment. See S. J. Lloyd, G. A. Botton, and W. M. Stobbs, J. Microsc. 180, 288 (1995).
37. S. J. Lloyd, G. A. Botton, and W. M. Stobbs, Inst. Phys. Conf. Ser. 147, 31 (1995).
38. D. H. Pearson, C. C. Ahn, and B. Fultz, Phys. Rev. B 50, 12 969 (1994).
39. The concept of “charge transfer” associated with alloying is controversial. See for example, Theory of Alloy phase formation, edited by L. H. Bennett (AIME, Warrendale, PA, 1980). Here only the possibility that the changes in the white lines could be explained by some form of charge redistribution between the alloy components is considered.
40. B. D. Cullity, Elements of X-ray Diffraction, 2nd ed. (Addison-Wesley, Reading MA, 1978).
41. E. Spiller and A. E. Rosenbluth, Proc. SPIE 563, 221 (1985).
42. The hole count was given by positioning the probe away from the foil edge and measuring the Cu signal. It is generated by stray scattering from the column generating x rays from the Cu surrounding the multilayer, and a further underestimate of the Fe content may result from the surface layer of sputter on the sample. See M. H. Loretto, Electron Beam Analysis of Materials, 2nd ed. (Chapman & Hall, London, 1994).
43. P. Rez has since calculated a scattering factor for Cu with a (Formula presented) configuration, which is very similar to the DT value.
44. P. Rez (private communication).
45. A. R. Preston (private communication).
46. A. Weickenmeier and H. Kohl, Acta Crystallogr. Sect. A: Found. Crystallogr. 47, 590 (1991).
47. R. J. Weiss, Proc. Phys. Soc. London 82, 281 (1963).
48. M. L. Huberman and M. Grimsditch, Phys. Rev. Lett. 62, 1403 (1989).
49. M. L. Huberman and M. Grimsditch, Phys. Rev. B 46, 7949 (1992).
50. J. P. Rogers III, P. H. Cutler, T. E. Feuchtwang, and A. A. Lucas, Surf. Sci. 181, 436 (1987).
51. M. Jalochowski, Prog. Surf. Sci. 48, 287 (1995).
52. C. Sommers and P. M. Levy, J. Phys. (France) 6, 1461 (1996).
53. C. S. Baxter and W. M. Stobbs, Nature (London) 322, 814 (1986).
54. M. O’Keefe and J. C. H. Spence, Acta Crystallogr., Sect. A: Found. Crystallogr. 50, 33 (1994).
55. M. D. Stiles, Phys. Rev. B 48, 7238 (1993).
56. S. S. Peng and H. J. F. Jansen, Ultramicroscopy 47, 361 (1992).
57. D. Li, M. Freitag, J. Pearson, Z. Q. Qiu, and S. D. Bader, Phys. Rev. Lett. 72, 3112 (1994).
58. W. J. M. de Jonge, P. J. H. Bloemen, and F. J. A. den Broeder, in Ultrathin Magnetic Structures (Ref. 3).
59. J. E. Bernard and A. Zunger, Appl. Phys. Lett. 65, 165 (1994).
60. M. Grimsditch, R. Bhadra, I. K. Schuller, F. Chambers, and G. Devane, Phys. Rev. B 42, 2923 (1990).
61. A. Cottrell, Introduction to the Modern Theory of Metals (Institute of Metals, London, 1988).
62. J. C. Jamieson, Science 139, 762 (1963).
63. M. Grimsditch, Superlattices Microstruct. 4, 677 (1988).
64. S. Andrieu, J. Hubsch, M. Piecuch, L. Hennet, and H. Fischer, in Magnetic Ultrathin Films, Multilayers and Surfaces Interfaces and Characterization, edited by B. T. Jonker, S. A. Chambers, R. F. C. Farrow, C. Chappert, R. Clarke, W. J. M. de Jonge, T. Egami, P. Grünberg, K. M. Krishnan, E. E. Marinero, C. Rau, and S. Tsunashima, MRS Synposia Proceedings No. 313 (Materials Research Society, Pittsburgh, 1993), p. 473.
65. T. Ueda, G. F. Simenson, W. D. Nix, and B. M. Clemens, in Structure and Properties of Multilayered Thin Films (Ref. 21), p. 279.