中文版
 

Dr. Fangfei Ming: Realization of a hole-doped Mott insulator on a triangular silicon lattice and its zero-bias-anomaly (2018/01/19)

( 2018-01-17 )

Title

Realization of a hole-doped Mott insulator on a triangular silicon lattice and its zero-bias-anomaly

 

Speaker

 

Dr. Fangfei Ming

The University of Tennessee, Knoxville, USA

 

Time

10:00am, January 19, 2018

Place

Room 9004 at the HFNL building

Brief Bio of the Speaker

明方飞博士于2007年毕业于西北大学物理系,于2012年获得香港中文大学博士学位,其后继续在香港中文大学做博士后,2014年起至今在田纳西大学诺克斯维尔分校做博士后。研究工作主要为在超高真空条件下使用各种表面科学的表征手段,特别是扫描隧道显微镜,研究表面结构的物理性质。近期的工作主要为电荷掺杂引起的表面相变。 

Abstract

The physics of doped Mott insulators is at the heart of some of the most exotic physical phenomena in materials research including insulator-metal transitions, colossal magneto-resistance, and high-temperature superconductivity in layered perovskite compounds. Advances in this field would greatly benefit from the availability of new material systems with similar richness of physical phenomena, but with fewer chemical and structural complications in comparison to oxides. Using scanning tunneling microscopy and spectroscopy (STM/STS), we show that such a system can be realized on a silicon platform. Adsorption of one-third monolayer of Sn atoms on a Si(111) surface produces a triangular surface lattice with half-filled dangling bond orbitals. Modulation hole-doping of these dangling bonds unveils clear hallmarks of Mott physics, such as spectral weight transfer and the formation of quasi-particle states at the Fermi level, well-defined Fermi contour segments, and a sharp singularity in the density of states. We further show that the maximum hole-density of this system increases with decreasing domain size as the area of the Mott insulating domains approaches the nanoscale regime. Concomitantly, STS data at 4.4 K reveal an increasingly prominent zero bias anomaly (ZBA). We consider two different scenarios as potential mechanisms for this ZBA: chiral dx2-y2+idxy wave superconductivity and a dynamical Coulomb blockade (DCB) effect. With a thorough experimental characterization, we conclude that the ZBA is predominantly due to a DCB effect, while a superconducting instability is absent or a minor contributing factor.

Reference:

[1] F. Ming, et. al., PRL 119, 266802 (2017)

[2] F. Ming, et. al., arXiv:1712.02736(to be published in PRB)


Seminar
 
[18-01-08]
[18-01-08]
[17-12-18]
[17-12-14]
[17-11-27]
[17-11-20]
[17-11-17]
[17-11-07]
Links
 
CopyRight@International Center for Quantum Eesign of Functional Materials
Counter :