Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 21: Poster I
MA 21.14: Poster
Dienstag, 13. März 2018, 09:30–13:00, Poster A
Novel method of setting exchange bias in tunnel magnetoresistance devices with laser annealing — •Apoorva Sharma1, Maria Almeida1,2, Sandra Busse3, Mathias Müller3, Patrick Matthes2, Horst Exner3, Stefan E. Schulz2, Dietrich R.T. Zahn1, and Georgeta Salvan1 — 1Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany — 2Fraunhofer ENAS, 09126 Chemnitz, Germany — 3Laserinstitut Hochschule Mittweid, Schillerstraße 10, 09648 Mittweida, Germany
Magnetic field sensors have become indispensable in a vast variety of modern devices, with applications ranging from basic research to industrial equipment. The so-called spintronic magnetoresistive effects, in particular the tunnel magnetoresistance can provide larger signal yields and sensitivities compared to well-established Hall and Anisotropy magnetoresistance technologies. The selective orientation of the magnetization depending on setting an exchange bias in micron size sensors, however, still represents a challenge. This can be achieved by laser annealing in conjunction with the suitable magnetic field. We investigated micromagnetic properties of IrMn/CoFeB/MgO/CoFeB tunnel junctions upon localized annealing with a 1064 nm IR laser, focusing on the magnetic properties of the exchanged coupled IrMn/CoFeB bilayers, namely the magnetization, coercivity, and exchange bias field. These were evaluated with SQUID-VSM and MOKE-magnetometry, as well as with a 4-point probe magnetoresistance measurement method. The exchange field set with laser-field-cooling was observed to be comparable with conventional methods.