Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 11: Thin Film Properties: Structure, Morphology and Composition (XRD, TEM, XPS, SIMS, RBS, AFM, ...): Session II

DS 11.3: Talk

Tuesday, March 13, 2018, 10:00–10:15, H 0111

Structural and magnetic properties of FePt-Tb alloy thin films — •Nataliia Safonova and Manfred Albrecht — Experimental physics IV, Institute of Physics, University of Augsburg, D-86159, Augsburg

Magnetic materials designed for ultrafast all-optical switching of magnetization are of high interest from a fundamental as well as technological point of view [1, 2]. In this study, two series of (FePt)(1-x)Tb(x) ternary alloy thin films with a thickness of about 10 nm were sputter deposited on MgO(100) substrates at 530°C (series I) and 700-770°C (series II). The Tb content x was varied in the range 5 - 28 at.%. Series I reveal limited L10 chemical ordering with an in-plane easy axis at room temperature. By addition of Tb higher than 11 at.%, a loss in crystallinity was observed. It is suggested that Tb is located as an interstitial atom to the FePt lattice, adding elastic stress to the lattice, eventually leading to amorphization of the local Tb environment. At low temperatures a spin reorientation transition (SRT), indicated by the appearance of strong perpendicular magnetic anisotropy (PMA), was observed. The SRT temperature increases linearly with addition of Tb. Higher deposition temperatures of 700-770 °C (series II) promote L10 chemical ordering with (001) orientation and strong PMA of 1.2 MJ/m3 at 300 K. However, with addition of Tb up to 6 at.%, PMA as well as coercivity get strongly reduced.

[1] A. Kirilyuk et al., Rev. Mod. Phys. 82, 2731 (2010).

[2] A. Hassdenteufel et al., Phys. Rev. B 91, 104431 (2015).