The new trilayer system NiMnSb/V/NiMnSb on MgO(001) was investigated by means of vibrating sample magnetometry (VSM), x-ray, and neutron reflectivity. VSM revealed a coercive field Oe and a hysteresis loop similar to that of an uncoupled ferromagnet. The x-ray and neutron reflectivity data proved that interface roughnesses of 10 Å are present. A detailed analysis yielded significant interdiffusion at the NiMnSb/V interfaces which is one possible explanation for the weak magnetoresistance effect measured in similar NiMnSb-based multilayer systems.
REFERENCES
1.
For an overview of GMR and exchange coupling see, e.g., Ultrathin Magnetic Structures, edited by B. Heinrich and J. A. C. Bland (Springer, Berlin, 1994), Vol. 2, or
S. S. P.
Parkin
, Annu. Rev. Mater. Sci.
25
, 357
(1995
), and references therein.2.
R.
Kabani
, M.
Terada
, A.
Roshko
, and J. S.
Moodera
, J. Appl. Phys.
67
, 4898
(1990
).3.
4.
J. F.
Bobo
, P. R.
Johnson
, M.
Kautzky
, F. B.
Mancoff
, E.
Tuncel
, R. L.
White
, and B. M.
Clemens
, J. Appl. Phys.
81
, 4164
(1997
).5.
J. A.
Caballero
, Y. D.
Park
, A.
Cabbibo
, J. R.
Childress
, F.
Petroff
, and R.
Morel
, J. Appl. Phys.
81
, 2740
(1997
).6.
C. T.
Tanaka
, J.
Nowak
, and J. S.
Moodera
, J. Appl. Phys.
81
, 5515
(1997
).7.
Ch.
Hordequin
, J. P.
Nozieres
, and J.
Pierre
, J. Magn. Magn. Mater.
183
, 225
(1998
).8.
J. A.
Caballero
, Y. D.
Park
, J. R.
Childress
, J.
Bass
, W.-C.
Chiang
, A. C.
Reilly
, W. P.
Pratt
, Jr., and F.
Petroff
, J. Vac. Sci. Technol. A
16
, 1801
(1998
).9.
10.
R B.
Helmholdt
, R. A.
de Groot
, F. M.
Mueller
, P. G.
van Engen
, and K. H. J.
Buschow
, J. Magn. Magn. Mater.
43
, 249
(1984
).11.
M. J.
Ott
, R. A. M.
van Woerden
, P. J.
van der Valk
, J.
Wijngaard
, C. F.
van Bruggen
, C.
Haas
, and K. H. J.
Buschow
, J. Phys.: Condens. Matter
1
, 2341
(1989
).12.
R. A.
de Groot
, F. M.
Mueller
, P. G.
van Engen
, and K. H. J.
Buschow
, Phys. Rev. Lett.
50
, 2024
(1983
).13.
J. H.
Wijngaard
, C.
Haas
, and R. A.
de Groot
, Phys. Rev. B
40
, 9318
(1989
).14.
15.
V. N.
Antonov
, P. M.
Oppeneer
, A. N.
Yaresko
, A. Ya.
Perlov
, and T.
Kraft
, Phys. Rev. B
56
, 13012
(1997
).16.
17.
J.-P.
Schlomka
, M. R.
Fitzsimmons
, M.
Lütt
, W.
Press
, and I.
Grigorov
, Physica B
248
, 140
(1998
).18.
J.-P. Schlomka, Untersuchung der Strukturellen und Magnetischen Eigenschaften von dünnen NiMnSb-Schichtsystemen (Verlag für Wissenschaft und Forschung, Berlin, 1999).
19.
The VSM measurement was performed with a film deposited on a large and 1 mm thick MgO substrate which was prepared at the same time and under the same conditions as the large sample. The volume of the magnetic material was calculated from the surface area, determined by weighting of the sample, times the thickness obtained from the x-ray measurement. The very small amount of magnetic material led to the noisy VSM measurement of Fig. 1.
20.
A.
Schreyer
, R.
Siebrecht
, U.
Englisch
, U.
Pietsch
, and H.
Zabel
, Physica B
248
, 349
(1998
).21.
M. Born and E. Wolf, Principles of Optics (Pergamon, Oxford, 1993).
22.
J. Lekner Theory of Reflection (Nijhoff, Dordrecht, 1987).
23.
The dispersion is given by with the complex atomic formfactor of atom k: classical electron radius, ρ(r): electron density, λ: x-ray wavelength, Z: total number of electrons per unit cell]. The sum is taken over all atoms of the unit cell. δ is proportional to the electron density away from absorption edges.
24.
For an overview on neutron reflectivity see, e.g.,
G. P.
Felcher
, Phys. Rev. B
24
, 1595
(1981
);Ultrathin Magnetic Structures, edited by J. A. C. Bland and B. Heinrich (Springer, Berlin, 1994), Vol. 1.
25.
The parametrized continuous refractive index profile was divided into 1.5 Å thin boxes and the reflectivity as calculated using the Parratt formalism for sharp interfaces (“slicing method”) [
L. G.
Parratt
, Phys. Rev.
95
, 359
(1954
);M. Tolan, X-ray Scattering from Soft Matter Thin Films: Materials Science and Basic Research, Springer Tracts in Modern Physics, Vol. 148 (Springer, Berlin, 1999)].
26.
A. L. Barabási and H. E. Stanley, Fractal Concepts in Surface Growth (Cambridge University Press, Cambridge, 1995).
27.
M.
Takeda
, Y.
Endoh
, A.
Kamijo
, and J.
Mizuki
, Physica B
248
, 14
(1998
).28.
29.
The calculated reflectivity has to be corrected by a geometry factor for which takes into account that at very small angles not all incoming radiation impinges onto the surface. is the “angle of full illumination” given by , with b the beam width and l the sample width [
A.
Gibaud
, G.
Vignaud
, and S. K.
Sinha
, Acta Crystallogr., Sect. A: Found. Crystallogr.
49
, 642
(1993
)]. Further, the FWHM of the specular peak should be half of the width of the primary beam even in the total external reflection regime.30.
M. K.
Sanyal
, J. K.
Basu
, A.
Datta
, and S.
Banerjee
, Europhys. Lett.
36
, 265
(1996
).31.
Landolt-Börnstein, Vol. III/19c, Heusler Alloys, edited by P. J. Webster and K. R. A. Ziebeck (Springer, Berlin, 1996).
32.
S. K.
Sinha
, E. B.
Sirota
, S.
Garoff
, and H. B.
Stanley
, Phys. Rev. B
38
2297
(1988
).
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