Synthetic domain walls in (TbFeGa/TbFe)_2 multilayers

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Bartolomé, Pablo
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Here we report the possibility of creating synthetic domain walls in nominal (Fe72Ga28/Tb33Fe67)_2 multilayers. The magnetization as a function of the temperature reveals the absence of Compensation temperature in the samples which can be understood considering an interdiffusion process that results in the formation of TbFeGa alloys at the nominal FeGa layers. Therefore, samples actually comprise TbFeGa and TbFe layers. The hysteresis loops exhibit magnetization steps related to the nucleation of domain walls formed because of the competition between different interactions: (i) the antiferromagnetic exchange coupling between the heavy rare earth (Tb) and the transition magnetic metal (Fe) inside each layer, (ii) the antiferromagnetic coupling between Tb and Fe at the interfaces, and (iii) the Zeeman energy. In good agreement with the experimental values, the nucleation field of the domain walls has been theoretically calculated taking into account the tilt of the magnetization with respect to the sample plane. Our experimental results indicate that by a proper thickness adjustment, it can be tuned, both the value of the nucleation field and the layer in which this firstly occurs. Experimental values for the exchange bias field have also been calculated.
©2020 IOP Publishing We thank 'CAI Tecnicas Fisicas' of UCM for SQUID measurements. We also thank ICTS-Instituto of Sistemas Optoelectronicos y Microtecnologia (ISOM) for using some of its facilities. This work has been financially supported through the projects MAT2015-66888-C3-3-R of the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER), and RTI2018-097895-B-C43 of the Spanish Ministry of Science, Innovation, and Universities.