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MA: Fachverband Magnetismus

MA 47: Poster III

MA 47.2: Poster

Thursday, March 21, 2024, 15:00–18:00, Poster D

Out-of-plane magnetoresistance in vortex magnetic tunnel junctions — •Johannes Demir, Tobias Peters, Karsten Rott, and Günter Reiss — Bielefeld University, Germany

We investigated the magnetoresistance (MR) in magnetic tunnel junctions (MTJs) where the free layer magnetization exhibits a magnetic vortex state. The MTJ is a standard tunnel magnetoresistance (TMR) stack with a thin Ta layer and a thickness varied FeB layer as the vortex layer on top, nanostructed into pillars with different diameters. MR measurements are performed by bonding the MTJ pillars to the contact pads of a chip carrier and applying a bias voltage in the mV range. Sweeping the out-of-plane (OOP) magnetic field between 2 T and -2 T we observe a nearly parabolic behaviour for the current flowing through the pillar saturating in dependence of the diameter of the pillar and the thickness of the vortex layer. Here, MR ratios of up to 60 % were achieved. Micromagnetic simulations reveal a tilting of the magnetization towards the magnetic field direction for both the vortex and reference layer. The evaluation of the simulations with a cosine-model [1] leads to a good agreement with the measurements.

[1] A. Tavassolizadeh et al., Appl. Phys. Lett. 102, 153104 (2013)

Keywords: Vortex; TMR; MTJ