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MA: Fachverband Magnetismus

MA 26: Thin Films: Magnetic Coupling Phenomena / Exchange Bias

MA 26.2: Vortrag

Dienstag, 21. März 2017, 14:15–14:30, HSZ 101

Improved thermal stability of doped MnN/CoFe exchange bias systems — •Mareike Dunz and Markus Meinert — Center for Spinelectronic Materials and Devices, Physics Department, Bielefeld University, Germany

In spinelectronics, the exchange bias effect is used to pin a ferromagnetic electrode to an antiferromagnetic film. This is crucial in GMR or TMR devices to allow for clearly separated switching states. Recently, we reported that polycrystalline MnN/CoFe bilayers show exchange bias fields of up to 1800 Oe at room temperature [1]. However, to make up for other commonly used antiferromagnets, some features of MnN like thermal stability and critical layer thickness require improvement. Here, we report on the effects of doping MnN with Fe, Si, or Y in order to optimize these properties.
Exchange bias systems with different doping concentrations and MnN layer thicknesses were prepared via reactive co-sputtering. Post-annealing series were performed to detect changes in the thermal stability. We show that doping with elements enhancing the nitrogen bonds in the MnN lattice, like Si or Y, indeed yields exchange bias systems that are stable up to higher temperatures. Y doped MnN layers with doping concentrations below 2% result in systems that show exchange bias fields higher than 1000 Oe for annealing temperatures up to 500^∘C.
[1] M. Meinert, B. Büker, D. Graulich, and M. Dunz. Large exchange bias in polycrystalline MnN/CoFe bilayers at room temperature. Phys. Rev. B. 92(14), 144408 (2015).