SYNTHESIS AND ATOMIC-SCALE CHARACTERIZATION OF TWO-DIMENSIONAL MAGNETIC MATERIALS

Abstract

The realization of long-range magnetic ordering with high Curie temperature in two-dimensional (2D) magnetic materials is highly appealing for their applications in data storage and quantum information processing. It is of great importance to develop advanced fabrication strategies for the large-scale synthesis of these 2D van der Waals (vdW) magnets with controllable thickness down to monolayer limit. In this thesis, we focus on controllable growth and atomic-scale characterization of representative 2D magnetic materials. We first fabricated a series of transition metal doped carbon nitride thin film with robust long-range ferromagnetic order beyond room temperature via the low-pressure chemical vapor deposition method. We then employed the low-temperature scanning tunnelling microscopy/spectroscopy (STM/STS) to systematically study the dielectric screening on the modulation of electronic correlation effects in a prototypical vdW magnet, namely monolayer CrBr3 grown on different substrates. Our studies reveal that substrate screening acts a tuning knob to effectively modulate the Coulomb interactions and inter-bands spacing between two correlated electronic states. In addition, we also investigated the catalytic applications of metal doped graphene, which can be regarded as a model ferromagnetic catalyst.