arXiv subjects

Marion A. van Midden

Publications and source records attributed to Marion A. van Midden.

2 recordsLinked to original sources

arXiv2021

Spatially intertwined superconductivity and charge order in 1T-TaSSe revealed by scanning tunneling spectroscopy

The interplay of different emergent phenomena -- superconductivity (SC) and domain formation -- appearing on different spatial and energy scales are investigated using high-resolution scanning tunneling spectroscopy (STS) in the prototypical transition metal dichalcogenide superconductor $1T$-TaSSe single crystals ($T_{SC} = 3.2$ K) at temperatures from 1 to 20 K. Our major observation is that while the SC gap size smoothly varies on the scale of $\lesssim 10$ nm, its spatial distribution is not correlated to the domain structure. On the other hand, there is statistically significant correlation of the SC gap $Δ_{SC}$ with spectral weight of the narrow band at the Fermi level formed from the same Ta $5d$ orbitals as the Mott-Hubbard band. We show that the narrow band follows the evolution of Hubbard bands in space, proving unambiguously its relation to the charge order. The correlations between the two suggest a non-trivial link between rapidly spatially varying charge order and superconductivity common in many quantum materials, and high-temperature superconductors in particular.

cond-mat.supr-con↗

arXiv2019

Configurational Electronic States in Layered Metallic Dichalcogenides

Mesoscopic irregularly ordered and even amorphous self-assembled electronic structures were recently reported in two-dimensional metallic dichalcogenides (TMDs), created and manipulated with short light pulses or by charge injection. Apart from promising new all-electronic memory devices, such states are of great fundamental importance, since such aperiodic states cannot be described in terms of conventional charge-density-wave (CDW) physics. In this paper we address the problem of metastable mesoscopic configurational charge ordering in TMDs with a sparsely filled charged lattice gas model in which electrons are subject only to screened Coulomb repulsion. The model correctly predicts commensurate CDW states corresponding to different TMDs at magic filling fractions $f_m=1/3,1/4,1/9,1/13,1/16$. Doping away from $f_m$ results either in multiple near-degenerate configurational states, or an amorphous state at the correct density observed by scanning tunnelling microscopy. Quantum fluctuations between degenerate states predict a quantum charge liquid at low temperatures, revealing a new generalized viewpoint on both regular, irregular and amorphous charge ordering in transition metal dichalcogenides.

cond-mat.str-el↗