CONTROLLING MAGNETIC PROPERTIES OF Fe/W (110) THIN FILMS BY ADSORBING ORGANIC MOLECULES ONTO THE SURFACES

• Main Author: SUKMA HUTAMA (NIM : 20511007); Pembimbing : Dr. Muhamad Abdulkadir Martoprawiro, AULIA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/15093
• Institution: Institut Teknologi Bandung

Understanding the interaction between adsorbed organic molecules and magnetic surfaces is important to understand how to control the magnetism of materials with adsorption. <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> Among many interesting materials, thin films containing magnetic and nonmagnetic metal layers appear as good candidates to build spintronic devices. In this work, magnetic properties of Fe/W (110) thin films, Fe/W (110) with adsorbed benzene molecules (Fe/W/benzene) and Fe/W (110) with adsorbed hexafluorobenzene molecules (Fe/W/hexafluorobenzene) have been investigated using density functional theory based approaches. Various exchange-correlation electron functionals such as <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> LDA, GGA, B3LYP and PBE0 have been used. Periodic and cluster calculations are performed in order to get insight on the important factors affecting the magnetic properties <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> of the magnetic layers. In the periodic calculations, the considered slabs consists in either 5 layers of W (110) or 5 layers of W (110) plus 1 layer Fe on each W layer side. <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> Our results show that the computed magnetic moment of the Fe layers depend moderately on the used functional in order 0.1 (mu)B. We also find a small magnetic moment in the W layer opposed to the one of the Fe layer. The results for Fe/W/benzene systems show that the magnetic moment of the Fe atoms is affected by the adsorption, and decreases <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> by approximately 0.5 (mu)B possibly due to the interaction between the p orbitals of benzene and the d orbitals of the Fe atoms. The adsorption of hexafluorobenzene can have more lowering effect on the Fe magnetic properties by approximately 0.2 (mu)B lower than adsorption with benzene. In the cluster calculations, the computed magnetic moments <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> for the Fe atoms are significantly larger than in the periodic calculations, which is most probably due to the lack of delocalization effects in our (small) finite size clusters. Addition of neighboring Fe andWatoms can add more delocalization effect to improve the results to be compared with periodic calculations. We then conclude that the magnetic moment of magnetic monolayers can be controlled by by adding molecules onto the surfaces.