Magnetic properties of perpendicularly magnetized ultrathin Pt/Co100-x-yFexBy/Pt films

  • C.J.T. Loermans

Student thesis: Master


In the field of spintronics an increasing amount of research is devoted to domain wall motion for application in a racetrack memory. To further advance this research we focus on perpendicularly magnetized Pt/Co100¡x¡yFexBy/Pt devices, which have a high anisotropy and narrow domain walls, which has a positive influence on the domain wall motion. To decrease the domain wall pinning potential, an amorphous magnetic layer of Co(Fe)B is used. In this thesis the magnetic properties of these ultrathin Pt/Co100¡x¡yFexBy/Pt devices are studied for many different compositions and thicknesses. To study these devices, two very sensitive measurement methods are used, the extraordinary Hall effect is used to measure the relative changes in magnetization, SQUID measurements supplement this with the measure- ment of absolute magnetic moments. With these two techniques we successfully measured the saturation magnetization Ms, the effective anisotropy Keff , the Curie temperature TC and the exchange stiffness A in ultrathin layers. To fully explain the EHE measurements we developed a 1-D model to describe the buckling of the magnetization. We found a high anisotropy for the amorphous compounds with 20 at% boron and especially a Pt/Co72Fe8B20/Pt device which showed anisotropy as high as Keff = 1:1 § 0:1MJ/m3 for the 5 ºA device. This makes a 5 ºA device of Pt/Co72Fe8B20/Pt the optimal choice for DW motion application.
Date of Award31 Aug 2009
Original languageEnglish
SupervisorReinoud Lavrijsen (Supervisor 1) & Henk J.M. Swagten (Supervisor 2)

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