강민구 교수

van der Waals two-dimensional (2D) semiconductors have emerged as a class of materials with promising device characteristics owing to the intrinsic band gap. For realistic applications, the ideal is to modify the band gap in a controlled manner by a mechanism that can be generally applied to this class of materials. Here, we report the observation of a universally tunable band gap in the family of bulk 2H transition metal dichalcogenides (TMDs) by in situ surface doping of Rb atoms. A series of

Abstract A central characteristic of living beings is the ability to learn from and respond to their environment leading to habit formation and decision making. This behavior, known as habituation, is universal among all forms of life with a central nervous system, and is also observed in single-cell organisms that do not possess a brain. Here, we report the discovery of habituation-based plasticity utilizing a perovskite quantum system by dynamical modulation of electron localization. Microscop

Abstract Recently, kagome lattice materials have emerged as a new model material platform for discovering and engineering novel quantum phases of matter. In this work, we elucidate the driving mechanism of the $$\sqrt{{{3}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msqrt> </mml:math> × $$\sqrt{{{3}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml

The authors have studied SmB${}_{6}$ and Ce${}_{3}$Bi${}_{4}$Pt${}_{3}$. Both of these Kondo insulators show a saturation of the increasing resistivity at low temperature that suggests an additional conduction channel and is consistent with the theoretical prediction that these systems should host robust surface states due to their nontrivial topology. While previous work has shown that the resistance saturation in SmB${}_{6}$ is due to conducting surface states, this work demonstrates that the

The kagome superconductor family AV_{3}Sb_{5} (A=Cs, K, Rb) emerged as an exciting platform to study exotic Fermi surface instabilities. Here, we use spectroscopic-imaging scanning tunneling microscopy (SI-STM) and angle-resolved photoemission spectroscopy (ARPES) to reveal how the surprising cascade of higher- and lower-dimensional density waves in CsV_{3}Sb_{5} is intimately tied to a set of small reconstructed Fermi pockets. ARPES measurements visualize the formation of these pockets generate

The two-dimensional kagome lattice hosts Dirac fermions at its Brillouin zone corners $K$ and ${K}^{\ensuremath{'}}$, analogous to the honeycomb lattice. In the density functional theory electronic structure of ferromagnetic kagome metal ${\mathrm{Fe}}_{3}{\mathrm{Sn}}_{2}$, without spin-orbit coupling, we identify two energetically split helical nodal lines winding along $z$ in the vicinity of $K$ and ${K}^{\ensuremath{'}}$ resulting from the trigonal stacking of the kagome layers. We find that

The study of elementary bosonic excitations is essential toward a complete description of quantum electronic solids. In this context, resonant inelastic x-ray scattering (RIXS) has recently risen to becoming a versatile probe of electronic excitations in strongly correlated electron systems. The nature of the radiation-matter interaction endows RIXS with the ability to resolve the charge, spin, and orbital nature of individual excitations. However, this capability has been only marginally explor