Berlin 2018 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 21: Poster I

MA 21.19: Poster

Dienstag, 13. März 2018, 09:30–13:00, Poster A

Magnetization profile at the interface between CoFeB and MgO determined by XRMR — •Eberhard Goering, Daan Boltje, and Gisela Schuetz — Max-Planck-Institut für Intelligente Systeme, 70569 Stuttgart

Sputtered CoFeB films sharing an interface with MgO play a key role in out-of-plane magnetized magnetic tunnel junctions STT-MRAM devices, based on perpendicular magnetic anisotropy (PMA). It is possible to switch the magnetic configuration using an electric field, directly affecting the PMA in the CoFeB layer [1].

Detailed information on the chemical dependant near the interface magnetic profile still lacks. We have performed x-ray resonant magnetic reflectometry (XRMR) and related x-ray magnetic circular dichroism (XMCD) experiments on the CoFeB-MgO system [2]. We obtain magneto optical properties and corresponding chemical and magnetic profiles for Co and Fe separately.

Partial oxidation of Fe during microfabrication is reported, where the oxidation state is reversibly controlled by an electric field [3]. Similarly, we find a 1 nm iron dead layer at the MgO interface and a 0.4 nm thick dead layer for cobalt at both interfaces of the CoFeB. Our results provide more information on the changes in magnetization profile due to oxidation.

[1] Wang et al., Nature Materials 11, 64 (2012).

[2] Macke et al., JoP: Condensed Matter 26, 363201 (2014).

[3] Bonell et al., Applied Physics Letters 102, 152401 (2013).