Magnetic anisotropy switching inTbCo thin films

Sammanfattning

Voltage-controlled magnetic anisotropy (VCMA) is the ability to change the magnetic anisotropy of a material by applying a voltage. This technique has the potential to be the foundation for the low-power computer memory of the future. In this study the potential for VCMA in thin films of TbCo with varying composition is evaluated. By applying a voltage to these films when they are submerged in an alkaline solution of KOH in water, hydrogen atoms can decouple from the water molecules and become absorbed in the films. This affects the anisotropy, a property which can be utilised in future applications. As-deposited TbCo films have a strong perpendicular magnetic anisotropy (PMA) which is verified by polar MOKE measurements. The thickness of the films is acquired through x-ray reflectivity (XRR). The films are then subject to charging in the electrolyte, where electrochemical measurements are also performed. Polar and longitudinal MOKE investigates anisotropy switching and the hydrogen content is analysed with nuclear reaction analysis (NRA) measurements at the Tandem facility at Uppsala University. The project has showed that TbCo experiences VCMA in a liquid electrolyte. If the main ion responsible is hydrogen is undetermined, since NRA measurements only show significant hydrogen content for one concentration of Tb.