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arXiv · 1912.03242

Superconductivity in a hole-doped Mott-insulating triangular adatom layer on a silicon surface

Xuefeng Wu·Fangfei Ming·Tyler S. Smith·Guowei Liu·Fei Ye·Kedong Wang·Steven Johnston·Hanno H. Weitering
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Abstract

Adsorption of one-third monolayer of Sn on an atomically-clean Si(111) substrate produces a two-dimensional triangular adatom lattice with one unpaired electron per site. This dilute adatom reconstruction is an antiferromagnetic Mott insulator; however, the system can be modulation-doped and metallized using heavily-doped p-type Si(111) substrates. Here, we show that the hole-doped dilute adatom layer on a degenerately doped p-type Si(111) wafer is superconducting with a critical temperature of 4.7 +- 0.3 K. While a phonon-mediated coupling scenario would be consistent with the observed TC, Mott correlations in the Sn-derived dangling-bond surface state could suppress the s-wave pairing channel. The latter suggests that the superconductivity in this triangular adatom lattice may be unconventional.

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Xuefeng Wu, Fangfei Ming, Tyler S. Smith, Guowei Liu, Fei Ye, Kedong Wang, Steven Johnston, Hanno H. Weitering. 2019-12-06. Superconductivity in a hole-doped Mott-insulating triangular adatom layer on a silicon surface. https://doi.org/10.1103/physrevlett.125.117001

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