10 Measuring Atomic Magnetic Moments in Magnetic Nanostructures …
255
Co L-edge, it is possible to independently probe the dynamic behaviour in each
section of the bilayer.
FMR measurements show two resonance states in the bilayer with applied static
fields of 3 and 37 mT labelled the optic mode and the acoustic mode, respectively. In
the acoustic mode, the magnetisation of both layers precesses in phase. The amplitude
is strongest in the NiFe layer, and decays as it penetrates into the CoFe layer. In
contrast, in the optic mode, magnetisations of the two layers precess in anti-phase
and the amplitude is greatest in the CoFe layer. XFMR data was measured at the Ni
and Co L 2 edges using circularly polarised X-rays with fixed helicity. The magnetic
excitation pulse was at 8 GHz (125 ps period) and Fig. 10.9a, b shows the delay
scans for the acoustic mode (at 37 mT) and optic mode (at 3 mT), respectively. In the
acoustic mode, the Co and Ni spins precess in phase while in the optic mode, they
are in anti-phase. The relative amplitudes confirm that the acoustic mode is mainly
driven by the Ni layer and the optic mode is mainly driven by the Co layer.
The amplitude and phase of the Co and Ni signals are plotted in Fig. 10.3c and
shows the behaviour expected of coupled driven oscillators.
References
1. J.L. Erskine, E.A. Stern, Phys. Rev. B 12, 5016 (1975)
2. G. Schütz, W. Wagner, W. Wilhelm, P. Kienle, R. Zeller, R. Frahm, G. Materlik, Phys. Rev.
Lett. 58, 737 (1987)
3. J. Stöhr and Y. Wu, New directions in research with third generation synchrotron radiation
sources, in NATO ASI Series E: Applied Sciences, eds. by A.S. Schlachter, F.J. Wuilleumier
(Kluwer 1994), p. 221
4. G. Van der Laan, A.I. Figueroa, Co-ord. Chem Rev. 277–278, 95 (2014)
5. J. Stöhr, J. Electr. Spectr. Re. Phenom. 75, 253 (1995)
6. B.T. Thole, P. Carra, F. Sette, G Laan van der, Phys. Rev. B 68, 1943 (1992)
7. P. Carra, B.T. Thole, M. Altarelli, X. Wang, Phys. Rev. Lett. 70, 694 (1993)
8. M. Altarelli, Phys. Rev. B 47, 597 (1993)
9. A. Ankudinov, J.J. Rehr, Phys. Rev. B 51, 1282 (1995)
10. C.T. Chen, Y.U. Idzerda, H.-J. Lin, N.V. Smith, G. Meigs, E. Chaban, G.H. Ho, E. Pelligrin, F.
Sette, Phys. Rev. Lett. 75, 152–155 (1995)
11. C. Binns and J. Blackman, Chapter 9, section 9.2.6, in Metallic Nanoparticles, ed. by. J.
Blackman (Elsevier, 2009). ISBN: 978-0-444-51240-6
12. P. Bruno, Phys. Rev. B 39, 865 (1989)
13. J. Nogués, I.K.J. Schuller, J. Magn. Magn. Mater. 192, 203–232 (1999)
14. A.E. Berkowitz, K.J. Takano, J. Magn. Magn. Mater. 200, 552–570 (1999)
15. B. Dieny, V.S. Speriosu, S.S.P. Parkin, B.A. Gurney, D.R. Wilhoit, D. Mauri, Phys. Rev. B 43,
1297–1300 (1991)
16. C. Binns, M.T. Qureshi, D. Peddis, S.H. Baker, P.B. Howes, A. Boatwright, S.A. Cavill, S.S.
Dhesi, L. Lari, R. Kröger, S. Langridge, Nanoletters 13, 3334–3339 (2013)
17. T. Funk, A. Deb, S.J. George, H. Wang, S.P. Cramer, Co-ord. Chem. Rev. 249, 3–30 (2005)
18. A.I. Figueroa, A.A. Baker, S.E. Harrison, K. Kummer, G. van der Laan, T. Hesjedal, J. Magn.
Magn. Mater. 422, 93–99 (2017)
19. S. Cherifi, R. Hertel, J. Kirschner, H. Wang, R. Belkhou, A. Locatelli, S. Heun, A. Pavlocska,
E. Bauer, J. Appl. Phys 98, 043901 (2005)
20. G. van der Laan, J. Electr. Spectr. Rel. Phenom. 220, 137–146 (2017)
255
Co L-edge, it is possible to independently probe the dynamic behaviour in each
section of the bilayer.
FMR measurements show two resonance states in the bilayer with applied static
fields of 3 and 37 mT labelled the optic mode and the acoustic mode, respectively. In
the acoustic mode, the magnetisation of both layers precesses in phase. The amplitude
is strongest in the NiFe layer, and decays as it penetrates into the CoFe layer. In
contrast, in the optic mode, magnetisations of the two layers precess in anti-phase
and the amplitude is greatest in the CoFe layer. XFMR data was measured at the Ni
and Co L 2 edges using circularly polarised X-rays with fixed helicity. The magnetic
excitation pulse was at 8 GHz (125 ps period) and Fig. 10.9a, b shows the delay
scans for the acoustic mode (at 37 mT) and optic mode (at 3 mT), respectively. In the
acoustic mode, the Co and Ni spins precess in phase while in the optic mode, they
are in anti-phase. The relative amplitudes confirm that the acoustic mode is mainly
driven by the Ni layer and the optic mode is mainly driven by the Co layer.
The amplitude and phase of the Co and Ni signals are plotted in Fig. 10.3c and
shows the behaviour expected of coupled driven oscillators.
References
1. J.L. Erskine, E.A. Stern, Phys. Rev. B 12, 5016 (1975)
2. G. Schütz, W. Wagner, W. Wilhelm, P. Kienle, R. Zeller, R. Frahm, G. Materlik, Phys. Rev.
Lett. 58, 737 (1987)
3. J. Stöhr and Y. Wu, New directions in research with third generation synchrotron radiation
sources, in NATO ASI Series E: Applied Sciences, eds. by A.S. Schlachter, F.J. Wuilleumier
(Kluwer 1994), p. 221
4. G. Van der Laan, A.I. Figueroa, Co-ord. Chem Rev. 277–278, 95 (2014)
5. J. Stöhr, J. Electr. Spectr. Re. Phenom. 75, 253 (1995)
6. B.T. Thole, P. Carra, F. Sette, G Laan van der, Phys. Rev. B 68, 1943 (1992)
7. P. Carra, B.T. Thole, M. Altarelli, X. Wang, Phys. Rev. Lett. 70, 694 (1993)
8. M. Altarelli, Phys. Rev. B 47, 597 (1993)
9. A. Ankudinov, J.J. Rehr, Phys. Rev. B 51, 1282 (1995)
10. C.T. Chen, Y.U. Idzerda, H.-J. Lin, N.V. Smith, G. Meigs, E. Chaban, G.H. Ho, E. Pelligrin, F.
Sette, Phys. Rev. Lett. 75, 152–155 (1995)
11. C. Binns and J. Blackman, Chapter 9, section 9.2.6, in Metallic Nanoparticles, ed. by. J.
Blackman (Elsevier, 2009). ISBN: 978-0-444-51240-6
12. P. Bruno, Phys. Rev. B 39, 865 (1989)
13. J. Nogués, I.K.J. Schuller, J. Magn. Magn. Mater. 192, 203–232 (1999)
14. A.E. Berkowitz, K.J. Takano, J. Magn. Magn. Mater. 200, 552–570 (1999)
15. B. Dieny, V.S. Speriosu, S.S.P. Parkin, B.A. Gurney, D.R. Wilhoit, D. Mauri, Phys. Rev. B 43,
1297–1300 (1991)
16. C. Binns, M.T. Qureshi, D. Peddis, S.H. Baker, P.B. Howes, A. Boatwright, S.A. Cavill, S.S.
Dhesi, L. Lari, R. Kröger, S. Langridge, Nanoletters 13, 3334–3339 (2013)
17. T. Funk, A. Deb, S.J. George, H. Wang, S.P. Cramer, Co-ord. Chem. Rev. 249, 3–30 (2005)
18. A.I. Figueroa, A.A. Baker, S.E. Harrison, K. Kummer, G. van der Laan, T. Hesjedal, J. Magn.
Magn. Mater. 422, 93–99 (2017)
19. S. Cherifi, R. Hertel, J. Kirschner, H. Wang, R. Belkhou, A. Locatelli, S. Heun, A. Pavlocska,
E. Bauer, J. Appl. Phys 98, 043901 (2005)
20. G. van der Laan, J. Electr. Spectr. Rel. Phenom. 220, 137–146 (2017)