Paul Miceli | Searcharxiv

arXiv2024

Emergent Spin Fluctuation and Structural Metastability in Self-Intercalated Cr$_{1+x}$Te$_2$ Compounds

Intercalated van der Waals (vdW) magnetic materials host unique magnetic properties due to the interplay of competing interlayer and intralayer exchange couplings, which depend on the intercalant concentration within the van der Waals gaps. Magnetic vdW compound chromium telluride, Cr$_{1+x}$Te$_2$, has demonstrated rich magnetic phases at various Cr concentrations, such as the coexistence of ferromagnetic and antiferromagnetic phases in Cr$_{1.25}$Te$_2$ (equivalently, Cr$_{5}$Te$_8$). The compound is induced by intercalating 0.25 Cr atom per unit cell within the van der Waals gaps of CrTe$_2$. In this work, we report a notably increased Curie Temperature and an emergent in-plane spin fluctuation by slightly reducing the concentration of Cr intercalants in Cr$_{1.25}$Te$_2$. Moreover, the intercalated Cr atoms form a metastable 2$\times$2 supercell structure that can be manipulated by electron beam irradiation. This work offers a promising approach to tuning magnetic and structural properties by adjusting the concentration of intercalated magnetic atoms.

cond-mat.mtrl-sci↗

arXiv2016

Wide bandgap semiconductor from a hidden 2D incommensurate graphene phase

Producing a usable semiconducting form of graphene has plagued the development of graphene electronics for nearly two decades. Now that new preparation methods have become available, graphene's intrinsic properties can be measured and the search for semiconducting graphene has begun to produce results. This is the case of the first graphene "buffer" layer grown on SiC(0001) presented in this work. We show, contrary to assumptions of the last forty years, that the buffer graphene layer is not commensurate with SiC. The new modulated structure we've found resolves a long standing contradiction where ab initio calculations expect a metallic buffer, while experimentally it is found to be a semiconductor. Model calculations using the new incommensurate structure show that the semiconducting $π$-band character of the buffer comes from partially hybridized graphene incommensurate boundaries surrounding unperturbed graphene islands.

cond-mat.mes-hall↗