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Abstract:
　　The rich physics of doped Mott insulators is at the heart of high-temperature superconductivity in complex oxide compounds, although the precise mechanism for high temperature superconductivity is still up for debate. Advances in this field would greatly benefit from the availability of new material systems with similar richness of physical phenomena, ideally those that are much less complex in structure and composition, and easier to model theoretically. Here we show that such a system could potentially be realized on a silicon surface. Adsorption of one-third monolayer of Sn atoms on a Si(111) surface produces a triangular surface lattice with half-filled dangling bonds. Modulation hole-doping of these dangling bonds unveils clear hallmarks of Mott physics, and additionally produces a sharp ‘van Hove’ singularity in the density of states just below the Fermi level. At a critical doping level, we observe a strong zero-bias anomaly in the local density of states, possibly signaling the formation of a magnetic or superconducting gap. These observations are remarkably similar to those made in complex oxide materials, including the high-temperature superconductors, but highly extraordinary within the realm of conventional sp-bonded semiconductor materials. They suggest that exotic quantum matter phases can be realized and engineered on silicon-based materials platforms.

Biosketch：
　　Hanno Weitering is a professor of physics at the University of Tennessee, Knoxville, working in the area of experimental condensed matter physics, with special emphasis on surfaces, interfaces, and ultrathin film materials. Prof. Weitering earned his PhD in 1991 from the University of Groningen in The Netherlands and completed a two year postdoc at the University of Pennsylvania under the direction of Prof. Ward Plummer before moving to Tennessee. Prof. Weitering’s research interests include correlated electron phenomena and electronic instabilities at surfaces, low-dimensional superconductivity, dilute magnetic semiconductors, and oxide heterostructures. He currently serves as Head of the Department of Physics and Astronomy, and as Deputy Director of the Joint Institute of Advanced Materials, which is a joint venture between the University of Tennessee and Oak Ridge National Laboratory. Prof. Weitering was elected Fellow of the American Physical Society in 2009.