Current induced magnetization switching (CIMS) and noise characterization of MgO based magnetic tunnel junctions (MTJs)


Prof. Tomasz Stobiecki, AGH Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Department of Electronics (mail)


Witold Skowroński (EAIE AGH)


Current induced magnetization switching (CIMS) and noise characterization of MgO based magnetic tunnel junctions (MTJs)

Foreign partner:

Prof. Günter Reiss and Prof. Andreas Hütten, Bielefeld University, D2 Thin Films & Physics of Nanostructures Universitätsstraße 25, 33615 Bielefeld

Brief description:

Spin eletronics is an expanding research field, which comprehends magnetic thin film devices exploiting the quantum spin states of the electron, apart from its charge, in order to boost the existing functionality of conventional electronics. The giant magnetoresistance effect, encountered in all-metal magnetic multilayers, has already found application in state-of-the-art hard disk read heads. Moreover, magnetic random access memory (MRAM), based on the tunnel magnetoresistance in ferromagnet-insulatorferromagnet junctions, is broadly anticipated to become the near future’s universal storage medium.

Base on the years of bilateral collaboration between AGH Department of Electronics group of Magnetic Multilayers (chaired by Prof. Tomasz Stobiecki) and University of Bielefeld, group of Thin Films & Physics of Nanostructures (lead by Prof. Günter Reiss) we have decided to jointly implement project Magnetic nanostructures for spin electronics applications in the frame of PhD studies. Because the stage of magnetic tunnel junctions (MTJs) with high tunnel magnetoresistance ratio (TMR) and low resistance area product (RA) has been achieved, now challenging from the applications point view are two tasks: optimization of the current density for magnetization switching in nanopillars (MRAM cells) and noise characterization of the pillars junctions. The so called spin torque switching will be investigated as well to further lower the size and enhance the performance of integrated spin electronic devices.

We propose preliminary title of the PhD thesis: Current induced magnetization switching (CIMS) and noise characterization of MgO based MTJs.

In the laboratory of Thin Films & Physics of Nanostructures at the University of Bielefeld, the stage of the deposition, nanolithography and preliminary characterization of the electrical and magnetic parameters of prepared exchange biased spin valve and pseudo-spin valve nanostructures will be realized. In order to optimize the TMR ratio and RA new ferromagnetic electrodes systems, as amorphous CoFeB and Heusler alloys Co2MnSi, and high crystalline ordered MgO tunnel barrier will be investigated, because theoretical calculations predict very high spin-polarization at the Fermi-level for these compounds. In the laboratory of the Magnetic Multilayers at AGH, the equipment for CIMS and noise measurements will be designed. The prepared multilayers will be characterized at AGH: electrically (TMR and I-V measurements), magnetically (MOKE magnetooptical Kerr effect, magnetometry and magnetic domain observations) and structurally (XRD and AFM).

Students international exchange:

Two 6-months visits of the PhD-student in Bielefeld is planned during the reporting period II and V. The Germany partner has clean room equipped by high vacuum sputtering and electron-lithography systems for MTJs preparation in the nanopillar form with spatial resolution below 10 nm. In the frame of two visits is expected preparation in the clean room of MTJs and preliminary characterization of the samples using this methods which are not available at AGH.

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