scholarly journals Superfluid Properties of Superconductors with Disorder at the Nanoscale: A Random Impedance Model

2020 ◽  
Vol 5 (2) ◽  
pp. 36
Author(s):  
Giulia Venditti ◽  
Ilaria Maccari ◽  
Marco Grilli ◽  
Sergio Caprara
Keyword(s):  
Superconducting State ◽  
Transition Metal Dichalcogenides ◽  
Mean Field ◽  
Metallic Matrix ◽  
Proximity Effects ◽  
Experimental Investigations ◽  
Impedance Model ◽  
Metal Dichalcogenides ◽  
Effective Medium Approach ◽  
Theoretical Analyses

Some two-dimensional superconductors like, e.g., LaAlO 3 /SrTiO 3 heterostructures or thin films of transition metal dichalcogenides, display peculiar properties that can be understood in terms of electron inhomogeneity at the nanoscale. In this framework, unusual features of the metal-superconductor transition have been interpreted as due to percolative effects within a network of superconducting regions embedded in a metallic matrix. In this work we use a mean-field-like effective medium approach to investigate the superconducting phase below the critical temperature T c at which the resistivity vanishes. Specifically, we consider the finite frequency impedance of the system to extract the dissipative part of the conductance and the superfluid stiffness in the superconducting state. Intriguing effects arise from the metallic character of the embedding matrix: upon decreasing the temperature below T c proximity effects may rapidly increase the superfluid stiffness. Then, a rather fragile superconducting state, living on a filamentary network just below T c , can be substantially consolidated by additional superconducting regions induced by proximity effect in the interstitial metallic regions. This mean-field prediction should call for further theoretical analyses and trigger experimental investigations of the superconducting properties of the above systems.

scholarly journals Strain engineering of 2D semiconductors and graphene: from strain fields to band-structure tuning and photonic applications

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Zhiwei Peng ◽  
Xiaolin Chen ◽  
Yulong Fan ◽  
David J. Srolovitz ◽  
Dangyuan Lei
Keyword(s):  
Optical Properties ◽  
Optical Measurement ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Strain Engineering ◽  
Experimental Investigations ◽  
Macroscopic Theory ◽  
Strain Fields ◽  
New Family ◽  
Metal Dichalcogenides

AbstractTwo-dimensional (2D) transition metal dichalcogenides (TMDCs) and graphene compose a new family of crystalline materials with atomic thicknesses and exotic mechanical, electronic, and optical properties. Due to their inherent exceptional mechanical flexibility and strength, these 2D materials provide an ideal platform for strain engineering, enabling versatile modulation and significant enhancement of their optical properties. For instance, recent theoretical and experimental investigations have demonstrated flexible control over their electronic states via application of external strains, such as uniaxial strain and biaxial strain. Meanwhile, many nondestructive optical measurement methods, typically including absorption, reflectance, photoluminescence, and Raman spectroscopies, can be readily exploited to quantitatively determine strain-engineered optical properties. This review begins with an introduction to the macroscopic theory of crystal elasticity and microscopic effective low-energy Hamiltonians coupled with strain fields, and then summarizes recent advances in strain-induced optical responses of 2D TMDCs and graphene, followed by the strain engineering techniques. It concludes with exciting applications associated with strained 2D materials, discussions on existing open questions, and an outlook on this intriguing emerging field.

scholarly journals Super-resolved Optical Mapping of Reactive Sulfur-Vacancies in Two-Dimensional Transition Metal Dichalcogenides

ACS Nano ◽  
2021 ◽  
Author(s):  
Miao Zhang ◽  
Martina Lihter ◽  
Tzu-Heng Chen ◽  
Michal Macha ◽  
Archith Rayabharam ◽  
...  
Keyword(s):  
Transition Metal ◽  
Optical Mapping ◽  
Transition Metal Dichalcogenides ◽  
Two Dimensional ◽  
Metal Dichalcogenides

Highly electroconductive and uniform WS2 film growth by sulfurization of W film using diethyl sulfide

2021 ◽  
Author(s):  
Yoobeen Lee ◽  
Jin Won Jung ◽  
Jin Seok Lee
Keyword(s):  
Transition Metal ◽  
Grain Boundaries ◽  
High Performance ◽  
Film Growth ◽  
Transition Metal Dichalcogenides ◽  
Electronic Systems ◽  
Intrinsic Defects ◽  
Diethyl Sulfide ◽  
Metal Dichalcogenides

The reduction of intrinsic defects, including vacancies and grain boundaries, remains one of the greatest challenges to produce high-performance transition metal dichalcogenides (TMDCs) electronic systems. A deeper comprehension of the...

Enhanced Photocurrent Response Speed in Charge-Density-Wave Phase of TiSe2-Metal Junctions

Nanoscale ◽  
2021 ◽  
Author(s):  
Thayer Walmsley ◽  
Yaqiong Xu
Keyword(s):  
Carrier Mobility ◽  
Density Wave ◽  
Transition Metal Dichalcogenides ◽  
Response Speed ◽  
Charge Carrier Mobility ◽  
Metal Dichalcogenides ◽  
Charge Density Wave Phase ◽  
Large Sheet ◽  
High Charge Carrier Mobility ◽  
Significant Attention

Group IVB transition metal dichalcogenides (TMDCs) have attracted significant attention due to their predicted high charge carrier mobility, large sheet current density, and enhanced thermoelectric power. Here, we investigate the...

scholarly journals VS2 as saturable absorber for Q-switched pulse generation

Nanophotonics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 2569-2576 ◽  
Author(s):  
Lu Li ◽  
Lihui Pang ◽  
Qiyi Zhao ◽  
Yao Wang ◽  
Wenjun Liu
Keyword(s):  
Saturable Absorber ◽  
Nonlinear Optical ◽  
Modulation Depth ◽  
Signal To Noise Ratio ◽  
Transition Metal Dichalcogenides ◽  
Laser Cavity ◽  
Pulse Generation ◽  
High Signal ◽  
Power Pulse ◽  
Metal Dichalcogenides

AbstractTransition metal dichalcogenides have been widely utilized as nonlinear optical materials for laser pulse generation applications. Herein, we study the nonlinear optical properties of a VS2-based optical device and its application as a new saturable absorber (SA) for high-power pulse generation. Few-layer VS2 nanosheets are deposited on the tapered region of a microfiber to form an SA device, which shows a modulation depth of 40.52%. After incorporating the microfiber-VS2 SA into an Er-doped fiber laser cavity, passively Q-switched pulse trains could be obtained with repetition rates varying from 95 to 233 kHz. Under the pump power of 890 mW, the largest output power and shortest pulse duration are measured to be 43 mW and 854 ns, respectively. The high signal-to-noise ratio of 60 dB confirms the excellent stability of the Q-switching state. To the best of our knolowdge, this is the first illustration of using VS2 as an SA. Our experimental results demonstrate that VS2 nanomaterials have a large potential for nonlinear optics applications.

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