ISSRNS 2012: Abstracts / Synchrotron Radiation in Natural Science Vol. 11, No 1 – 2 (2012) P 35
XAS/XMCD STUDIES OF Pt/Co/Pt NANOSTRUCTURES WITH OUT-OF-PLANE MAGNETIZATION INDUCED BY Ga
+IONS LOW FLUENCE IRRADIATION
P. Mazalski1∗, Z. Kurant1, A. Maziewski1, M.O. Liedke2, J. Fassbender2, L.T. Baczewski3, A. Wawro3, A. Rogalev4, and F. Wilhelm4
1Laboratory of Magnetism, Faculty of Physics, University of Bia lystok, Lipowa 41, 15–424 Bia lystok, Poland
2Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
3Institute of Physics, Polish Academy of Science, Aleja Lotnik´ow 32, 02–668 Warszawa, Poland
4European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble Cedex, France Keywords: synchrotron radiation, irradiation, magnetooptics
∗e-mail : piotrmaz@uwb.edu.pl
Magnetic properties of ultrathin films are usu- ally tuned by varying the film thickness, chemical composition or structure (see e.g. [1, 2]). It has been demonstrated that magnetic properties of thin films with perpendicular magnetic anisotropy of in- terfacial origin may be also tuned by ions irradia- tion [3]. A Pt/Co/Pt trilayer irradiated by different ions exhibits the out-of-plane to in-plane magneti- zation reorientation phase transition. Moreover, it was shown that an ion irradiation-driven intermix- ing and disordering at the Co-Pt interfaces was in- ducing a reduction of the anisotropy, coercivity, and Curie temperature.
In our recent paper [4] we have presented a new effect — remarkable change of a magnetic
Figure 1 : Remnant polar Kerr rotation θREM of Pt/Co(3.3 nm)/Pt film as a function of Ga+ irradia- tion fluence D. Green region — non-irradiated sample.
Arrows show schematically the magnetization direction.
anisotropy in the Pt/Co(2.6 nm)/Pt (deposited by sputtering technique) induced by an uniform low fluence Ga+ion irradiation at 30 keV. With increas- ing fluence D magnetization rotates from in-plane to out-of-plane state and then back to in-plane state.
Very recently the second up-turn of the magnetiza- tion was observed at the higher irradiation fluence [5]. Low dose Ga-ion irradiation creation of out-of- plane magnetization branch is illustrated in Fig. 1.
We propose that the origin of the observed out- of-plane magnetization state induced by ions irradi- ation is due to creation of strongly anisotropic Co-Pt L10 phase. This hypothesis is supported by mea- surement of K-edge X-ray absorption (XAS) and X-ray Magnetic Circular Dichroism (XMCD) on the ID12 ERSF beamline. The measurements were per- formed on: Pt/Co/Pt samples both as deposited film and irradiated one with the fluence creating the out-of-plane magnetization state and a refer- ence sample of L10Co0.5Pt0.5thin film. The XMCD spectrum of the irradiated sample is interpreted as the superposition of pure Co and L10 CoPt alloy contributions. TRIDYN [6] simulations, for differ- ent Ga+ ion fluence, were performed in order to corroborate these findings.
Acknowledgments: This work was supported by the following projects: SPINLAB — EU program Innova- tive Economy, Priority 2.2, SPIRIT European Commu- nity — contract no. 227012, ESRF/73/2006.
References
[1] M. Kisielewski, Phys. Rev. Lett. 89 (2002) 87203.
[2] A. Stupakiewicz, Phys. Rev. Lett. 101 (2008) 217202.
[3] C. Chappert, Science 280 (1998) 1919.
[4] J. Jaworowicz, Appl. Phys. Lett. 95 (2009) 022502.
[5] A. Maziewski, Phys. Rev. B 85 (2012) 054427.
[6] W. M¨oller, Comp. Phys. Commun. 51 (1988) 355.
115
!["Uniwersytet przyszłości: wyzwania i modele polityki", Dominik Antonowicz, Warszawa 2005 : [recenzja]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==)