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Ti periodic multilayer
Physica B 276}278 (2000) 700}701
Observation of peculiarities in magnetic o!-specular polarized neutron scattering from rough interfaces in Co/Ti periodic multilayer V.G. Syromyatnikov *, B.P. Toperverg , R. Siebrecht, A. Menelle, N.K. Pleshanov , V.M. Pusenkov , A.F. Schebetov , Z.N. Soroko , V.A. Ul'yanov Neutron Research Department, Petersburg Nuclear Physics Institute, 188350 Gatchina, St. Petersburg, Russia Institut Laue-Langevin, 156 Ave. des Martyrs, B.P. 156, F-38042 Grenoble Cedex 9, France Laboratoire Le& on Brillouin (CEA-CNRS), CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
Abstract The experimental results on polarized neutron magnetic o!-specular scattering from periodic multilayer 60Co/Ti are presented. The peculiarities in transverse di!use scans (TDS) (rocking curves), as manifestations of dynamical e!ects in o!-specular polarised neutron scattering have been observed for few characteristic magnitudes of magnetic "eld. 2000 Elsevier Science B.V. All rights reserved. Keywords: Interfaces; Polarized neutrons; Re#ectometer; Roughness
At present time the properties of multilayered thin "lm structures are under extensive investigations by use of a variety of di!erent methods, and in particular, by means of the neutron re#ectometry. This method is especially suitable to study such properties of magnetic thin "lms and multilayers, as GMR, exchange coupling between ferromagnetic layers, interdi!usion, domain structure, etc. It is known that the interfacial roughnesses have considerable impact on di!erent properties of magnetic multilayers and they may be successfully studied in the experiments on o!-specular polarised neutron scattering. A number of remarkable features in the scattering pattern are observed if the roughness on interfaces is conformally correlated [1,2]. Magnetic o!-specular polarised neutron scattering may provide information on the correlations between the atomic roughnesses and the magnetic inhomogeneities evolution in the process of the multilayer magnetization [3,4]. The experiments on the
* Corresponding author. Tel.: #7-81271-46973; fax: #781271-39053. E-mail address: [email protected], [email protected] (V.G. Syromyatnikov)
o!-specular polarised neutron scattering from rough interfaces in periodic (with 60 bilayers) Co/Ti and Fe/Al multilayers on the glass substrates in saturating magnetic "eld have been carried out on time-of-#ight neutron re#ectometer EROS (Saclay) in polarisation mode [5]. Anomalous peaks on the o!-specular quasi-Bragg scattering sheets were observed for both the samples. Here we report the results of the "eld dependences of the o!-specular scattering patterns measured on the same 60Co(101 As )/Ti(84 As ) multilayer at the neutron re#ectometer ADAM with j"4.41 As and *j/j"0.006. In the chosen range of magnetic "elds the incident collimation beam had an angular divergence of 0.13 and a polarisation of 0.96. The polarizing e$ciency P of the sample was measured at the position of the "rst-order Bragg specular re#ection dependent on the magnetic "eld H applied within the sample surface plane. It follows from the measurements that the sample was magnetized antiparallel to the "eld H if H(19.7 Oe and the magnetization direction is #ipped to the state parallel to the "eld H at H'19.7 Oe. The magnetic o!-specular scattering intensity has been measured in the geometry of angular scans by the sample (rocking curves or transverse di!use scans (TDS)) at three "xed positions of the detector,
0921-4526/00/$ - see front matter 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 5 2 6 ( 9 9 ) 0 1 4 4 4 - 1
V.G. Syromyatnikov et al. / Physica B 276}278 (2000) 700}701
Fig. 1. Transverse di!use scans for the second-order Bragg re#ection (Q 0.067 As \) for both spin states of neutrons and X for three values of magnetic "eld H, applied within the sample plane.
which are determined by Bragg re#ection of "rst order, second order and third order with Q 0.035, 0.067, X 0.101 As \ , correspondingly. Measurements of TDS have been carried out for both spin states of neutron and for three characteristic magnitudes of magnetic "eld H, applied to the sample: H "19.7 Oe * demagnetized state, P 0; H "22.9 Oe * partially demagnetized state, P 0.5; H "1730 Oe * saturated state of the sample, P"P . The data are presented in the coordinates Q ,
V where Q is the in-plane, while Q * out-of-plane comV X ponents of the momentum transfer Q. The anomalous peaks (satellites) for Q $0.0008 As \ for both V spin components in TDS across the second order Bragg re#ection (Q 0.067 As \) (see Fig. 1) have been obX
701
served. As seen in the "gure for (#) spin state neutron for H "1730 Oe (squares) two satellite peaks have in tensities even higher than a specular peak for Q "0. V A small dip for Q $0.0025 As \ in TDS of third-order V Bragg re#ection (Q 0.101 As \) for (#) spin state was X also recorded. Increasing of scattering in small "elds and alteration of satellites dependent on magnetic "eld were detected as well (see Fig. 1). The satellites and dips in TDS were explained in terms of distorted wave Born approximation (DWBA) in Refs. [5,6], as a manifestation of the dynamical e!ects in o!-specular polarised neutron scattering, when Bragg conditions are satis"ed for the neutron waves incident on, and for outgoing from the multilayered structure. To the best of our knowledge, it is the "rst study of the process of o!-specular polarized neutron scattering from rough interfaces in periodic magnetic multilayer, where peculiarities of o!-specular scattering are so strong and where observed e!ects are related to the conformal correlation in the magnetic inhomogeneities presumably originated from the magnetic stray "elds. A quantitative description of these features is in progress.
References [1] [2] [3] [4]
V.G. Syromyatnikov, et al., Preprint PNPI-2006, 1994. V.G. Syromyatnikov et al., Physica B 234}236 (1997) 475. M. Takeda et al., Physica B 248 (1998) 14. V.A. Ul'yanov et al., BENSC Experimental Reports, 1997, p. 122. [5] V.G. Syromyatnikov et al., Physica B 267}268 (1999) 190. [6] S.K. Sinha, Materials Research Society Symposia Proceedings No 376, MRS, Boston, 1995, p. 175.
Observation of peculiarities in magnetic o!-specular polarized neutron scattering from rough interfaces in Co/Ti periodic multilayer V.G. Syromyatnikov *, B.P. Toperverg , R. Siebrecht, A. Menelle, N.K. Pleshanov , V.M. Pusenkov , A.F. Schebetov , Z.N. Soroko , V.A. Ul'yanov Neutron Research Department, Petersburg Nuclear Physics Institute, 188350 Gatchina, St. Petersburg, Russia Institut Laue-Langevin, 156 Ave. des Martyrs, B.P. 156, F-38042 Grenoble Cedex 9, France Laboratoire Le& on Brillouin (CEA-CNRS), CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
Abstract The experimental results on polarized neutron magnetic o!-specular scattering from periodic multilayer 60Co/Ti are presented. The peculiarities in transverse di!use scans (TDS) (rocking curves), as manifestations of dynamical e!ects in o!-specular polarised neutron scattering have been observed for few characteristic magnitudes of magnetic "eld. 2000 Elsevier Science B.V. All rights reserved. Keywords: Interfaces; Polarized neutrons; Re#ectometer; Roughness
At present time the properties of multilayered thin "lm structures are under extensive investigations by use of a variety of di!erent methods, and in particular, by means of the neutron re#ectometry. This method is especially suitable to study such properties of magnetic thin "lms and multilayers, as GMR, exchange coupling between ferromagnetic layers, interdi!usion, domain structure, etc. It is known that the interfacial roughnesses have considerable impact on di!erent properties of magnetic multilayers and they may be successfully studied in the experiments on o!-specular polarised neutron scattering. A number of remarkable features in the scattering pattern are observed if the roughness on interfaces is conformally correlated [1,2]. Magnetic o!-specular polarised neutron scattering may provide information on the correlations between the atomic roughnesses and the magnetic inhomogeneities evolution in the process of the multilayer magnetization [3,4]. The experiments on the
* Corresponding author. Tel.: #7-81271-46973; fax: #781271-39053. E-mail address: [email protected], [email protected] (V.G. Syromyatnikov)
o!-specular polarised neutron scattering from rough interfaces in periodic (with 60 bilayers) Co/Ti and Fe/Al multilayers on the glass substrates in saturating magnetic "eld have been carried out on time-of-#ight neutron re#ectometer EROS (Saclay) in polarisation mode [5]. Anomalous peaks on the o!-specular quasi-Bragg scattering sheets were observed for both the samples. Here we report the results of the "eld dependences of the o!-specular scattering patterns measured on the same 60Co(101 As )/Ti(84 As ) multilayer at the neutron re#ectometer ADAM with j"4.41 As and *j/j"0.006. In the chosen range of magnetic "elds the incident collimation beam had an angular divergence of 0.13 and a polarisation of 0.96. The polarizing e$ciency P of the sample was measured at the position of the "rst-order Bragg specular re#ection dependent on the magnetic "eld H applied within the sample surface plane. It follows from the measurements that the sample was magnetized antiparallel to the "eld H if H(19.7 Oe and the magnetization direction is #ipped to the state parallel to the "eld H at H'19.7 Oe. The magnetic o!-specular scattering intensity has been measured in the geometry of angular scans by the sample (rocking curves or transverse di!use scans (TDS)) at three "xed positions of the detector,
0921-4526/00/$ - see front matter 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 5 2 6 ( 9 9 ) 0 1 4 4 4 - 1
V.G. Syromyatnikov et al. / Physica B 276}278 (2000) 700}701
Fig. 1. Transverse di!use scans for the second-order Bragg re#ection (Q 0.067 As \) for both spin states of neutrons and X for three values of magnetic "eld H, applied within the sample plane.
which are determined by Bragg re#ection of "rst order, second order and third order with Q 0.035, 0.067, X 0.101 As \ , correspondingly. Measurements of TDS have been carried out for both spin states of neutron and for three characteristic magnitudes of magnetic "eld H, applied to the sample: H "19.7 Oe * demagnetized state, P 0; H "22.9 Oe * partially demagnetized state, P 0.5; H "1730 Oe * saturated state of the sample, P"P . The data are presented in the coordinates Q ,
V where Q is the in-plane, while Q * out-of-plane comV X ponents of the momentum transfer Q. The anomalous peaks (satellites) for Q $0.0008 As \ for both V spin components in TDS across the second order Bragg re#ection (Q 0.067 As \) (see Fig. 1) have been obX
701
served. As seen in the "gure for (#) spin state neutron for H "1730 Oe (squares) two satellite peaks have in tensities even higher than a specular peak for Q "0. V A small dip for Q $0.0025 As \ in TDS of third-order V Bragg re#ection (Q 0.101 As \) for (#) spin state was X also recorded. Increasing of scattering in small "elds and alteration of satellites dependent on magnetic "eld were detected as well (see Fig. 1). The satellites and dips in TDS were explained in terms of distorted wave Born approximation (DWBA) in Refs. [5,6], as a manifestation of the dynamical e!ects in o!-specular polarised neutron scattering, when Bragg conditions are satis"ed for the neutron waves incident on, and for outgoing from the multilayered structure. To the best of our knowledge, it is the "rst study of the process of o!-specular polarized neutron scattering from rough interfaces in periodic magnetic multilayer, where peculiarities of o!-specular scattering are so strong and where observed e!ects are related to the conformal correlation in the magnetic inhomogeneities presumably originated from the magnetic stray "elds. A quantitative description of these features is in progress.
References [1] [2] [3] [4]
V.G. Syromyatnikov, et al., Preprint PNPI-2006, 1994. V.G. Syromyatnikov et al., Physica B 234}236 (1997) 475. M. Takeda et al., Physica B 248 (1998) 14. V.A. Ul'yanov et al., BENSC Experimental Reports, 1997, p. 122. [5] V.G. Syromyatnikov et al., Physica B 267}268 (1999) 190. [6] S.K. Sinha, Materials Research Society Symposia Proceedings No 376, MRS, Boston, 1995, p. 175.