Dinh Loc Duong

Affiliation: Center for Integrated Nanostructure Physics, IBS, Korea

Date: November 19, 2020; 16:00 – 17:00

The seminar will be held online, if you want to join the meeting, please, write to us at info@qns.science.

Diluted Magnetic Semiconductors in Flatland and Beyond

In the first part of this talk, the evidence of the long-range magnetic order in V-doped WSe2 semiconductors will be presented. The magnetic domains of the long-range ferromagnetic order are observed by magnetic force microscopy at room temperature. More importantly, the magnetic domains can be modulated by a gate bias, which is concrete evidence for the ferromagnetic semiconducting characteristics. The mechanism behind the formation of the long-range order will be also discussed and investigated through scanning tunneling spectroscopy and density functional theory.

In the second part, the giant Zeeman shift from the spin-polarized state in WSe2doped with a small amount of vanadium atoms (~0.15%) by investigating resonant magneto tunneling spectroscopy of a vertical graphite/V-WSe2/graphiteheterojunction will be discussed. The p-type character of the doping state is located near the valence band, substantially shifted under an external magnetic field at 7.8 meV/T with a giant g factor of approximately 135, an order of magnitude higher than that of other 2D magnetic semiconductors. The evidence of the spin-polarized band edges of V-doped WSe2 is also confirmed by circular-polarized photoluminescence.

In the last part, some preliminary observations of possible spin-frustration as well as topological characteristics in V-doped WSe2 will be presented.