New research enables silicon-based non-traditional superconductivity

Recently, Ming Fangfei, associate professor of the School of Electronics and Information Engineering (School of Microelectronics) of Sun Yat-sen University, and the team of Wang Kedong, associate professor of Southern University of Science and Technology, and Weitering, professor of the University of Tennessee, have cooperated to make important progress in the research of silicon-based topological superconductivity. The research was published as a cover article in Nature Physics. Ming Fangfei is the first author of the paper, and Sun Yat-sen University is the first completion unit.

Cover of the current issue. Photo courtesy of the research team

With the development of electronic information technology, superconductors have been given more important functions – the preparation of qubits and quantum computers. Silicon is the basic material of the current electronic information industry, but it is often regarded as a “traditional” or “replaced” material in future research on new electronic devices, in part because it is believed that it is difficult to achieve novel quantum effects in SP electronic systems with weak interactions.

The research team achieved silicon-based non-traditional superconductivity by cleverly designing the two-dimensional structure and doping method of the silicon surface. In the prepared system, a 1/3 monolayer of tin atoms with the same tetravalence is introduced on the termination surface of Si(111) to form a sparse triangular lattice to achieve a two-dimensional structure with strong correlation electronics. Furthermore, by placing the boron element in the subsurface layer and arranging it regularly, a high concentration of holes and non-destructive hole doping of the sparse lattice is realized. After doping, the structure changes from Moott insulator to superconductor, and the superconducting strength also changes significantly with the doping concentration. Although its superconducting temperature (≤9 K) is still significantly lower than that of liquid nitrogen (77 K), its superconducting physical properties are very similar to high-temperature superconductivity and belong to non-classical superconductivity.

In addition, the silicon-based two-dimensional lattice has triple symmetry, and its superconducting lowest energy state can be superimposed by two different d-sequence parameters, and different chiral characteristics are presented according to different superposition methods, that is, chiral d-wave superconductivity. The research team used scanning tunneling microscopy to measure the superconductivity properties under ultra-low temperature and magnetic field conditions with high precision, and obtained strong evidence of chiral D-wave superconductivity. This is a novel topological state of matter that people aspire to achieve, with the potential to prepare qubits and realize quantum computing, and the realization of this state of matter in silicon systems will likely help quantum technology to large-scale applications. (Source: China Science News Zhu Hanbin)

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