Bulk quantum transport measurements of Cd${}_{3}$As${}_{2}$ provide further evidence that it is a 3D Dirac Semimetal - a quantum state of matter whose properties resemble a 3D analog of graphene.

Quantum Transport Evidence for the Three-Dimensional Dirac Semimetal Phase in Cd 3 As 2

It has been a great challenge to achieve the direct light manipulation of matter on a bulk scale. In this work the direct light propulsion of matter is observed on a macroscopic scale using a bulk graphene-based material. The unique structure and properties of graphene, and the novel morphology of the bulk three-dimensional linked graphene material make it capable not only of absorbing light at various wavelengths but also of emitting energetic electrons efficiently enough to drive the bulk material, following Newtonian mechanics. Thus, the unique photonic and electronic properties of individual graphene sheets are manifested in the response of the bulk state. These results offer an exciting opportunity to bring about bulkscale light manipulation with the potential to realize long-sought applications in areas such as the solar sail and space transportation driven directly by sunlight.

Macroscopic and direct light propulsion of bulk graphene material

Performance enhancement can be realized in p-type Bi2Te3 but hardly in n-type Se-modified Bi2Te3 alloys fabricated by powder processing as compared with conventional ingots. To reveal the reasons and investigate the optimal Se content in fine-grained n-type Bi2Te3−xSex materials processed by mechanical alloying (MA) and spark plasma sintering (SPS), the amount of Se was varied in a wide range and electrical transport properties were investigated and discussed in association with the results of Hall measurements. Thermal transport properties were also studied with Raman spectra. It is revealed that different concentrations of point defects are induced by changing the Se content x from 0 to 1.0 in Bi2Te3−xSex. The point defects and their interaction (including donor-like effects) not only largely change the carrier concentration and mobility, but also enhance the phonon scattering that would lead to a decrease of thermal conductivity. Consequently, the optimal composition is confirmed as Bi2Te2.2Se0.8 with a corresponding carrier concentration of 4.5 × 1019 cm−3 and a maximum ZT value of 0.82 at 473 K, approximately 35% increased than that obtained at optimal Bi2Te2.7Se0.3 conventionally used for ingots. This work indicates that the point defects as well as their interaction during MA and SPS shift the optimal Se content from traditional x = 0.3 to x = 0.8 in n-type Bi2Te3−xSex, demonstrating the importance of comprehensive control of point defects by adjusting the Se content for different processes.

Electrical and thermal transport properties of spark plasma sintered n-type Bi2Te3−xSex alloys: the combined effect of point defect and Se content

A double Dirac cone is realized at the center of the Brillouin zone of a two-dimensional phononic crystal (PC) consisting of a triangular array of core-shell-structure cylinders in water. The double Dirac cone is induced by the accidental degeneracy of two double-degenerate Bloch states. Using a perturbation method, we demonstrate that the double Dirac cone is composed of two identical and overlapping Dirac cones whose linear slopes can also be accurately predicted from the method. Because the double Dirac cone occurs at a relatively low frequency, a slab of the PC can be mapped onto a slab of zero refractive index material by using a standard retrieval method. Total transmission without phase change and energy tunneling at the double Dirac point frequency are unambiguously demonstrated by two examples. Potential applications can be expected in diverse fields such as acoustic wave manipulations and energy flow control.

/pdf/double-dirac-cones-in-phononic-crystals-27ouhu5vog.pdf

Double Dirac cones in phononic crystals

Although signatures of superconductivity in Dirac semimetals have been reported, for instance by applying pressure or using point contacts, our understanding of the topological aspects of Dirac semimetal superconductivity is still developing. Here, we utilize nanoscale phase-sensitive junction technology to induce superconductivity in the Dirac semimetal Bi1−xSbx. Our radiofrequency irradiation experiments then reveal a significant contribution of 4π-periodic Andreev bound states to the supercurrent in Nb–Bi0.97Sb0.03–Nb Josephson junctions. The conditions for a substantial 4π contribution to the supercurrent are favourable because of the Dirac cone’s very broad transmission resonances and a measurement frequency faster than the quasiparticle poisoning rate. In addition, we show that a magnetic field applied in the plane of the junction allows tuning of the Josephson junctions from 0 to π regimes. Our results open the technologically appealing avenue of employing the topological bulk properties of Dirac semimetals for topological superconductivity research and topological quantum computer development.

/pdf/4p-periodic-andreev-bound-states-in-a-dirac-semimetal-1a4pu8ympj.pdf

4π-periodic Andreev bound states in a Dirac semimetal

Bismuth antimony (Bi1−xSbx) is one of the most important materials systems for fundamental materials science, condensed matter physics, low temperature thermoelectrics, infrared applications, and beyond. The bulk materials have been studied for many decades. Recently, nanoscience and nanotechnology has been introduced to this materials system, which has brought much more interest and attention for both research and applications. The present article reviews the up-to-date achievements on electronic properties of nanostructured Bi1−xSbx, and points out future directions for scientific research in this field.

Electronic properties of nano-structured bismuth-antimony materials

The electronic band structures of Bi1–xSbx thin films can be varied as a function of temperature, pressure, stoichiometry, film thickness, and growth orientation. We here show how different anisotropic single-Dirac-cones can be constructed in a Bi1–xSbx thin film for different applications or research purposes. For predicting anisotropic single-Dirac-cones, we have developed an iterative-two-dimensional-two-band model to get a consistent inverse-effective-mass-tensor and band gap, which can be used in a general two-dimensional system that has a nonparabolic dispersion relation as in the Bi1–xSbx thin film system.

Constructing Anisotropic Single-Dirac-Cones in Bi1–xSbx Thin Films

The electronic band structures of Bi${}_{1-x}$Sb${}_{x}$ thin films can be varied as a function of temperature, pressure, stoichiometry, film thickness and growth orientation. We here show how different anisotropic single-Dirac-cones can be constructed in a Bi${}_{1-x}$Sb${}_{x}$ thin film for different applications or research purposes. For predicting anisotropic single-Dirac-cones, we have developed an iterative-two-dimensional-two-band model to get a consistent inverse-effective-mass-tensor and band-gap, which can be used in a general two-dimensional system that has a non-parabolic dispersion relation as in a Bi${}_{1-x}$Sb${}_{x}$ thin film system.

Prediction of Anisotropic Single-Dirac-Cones in Bi${}_{1-x}$Sb${}_{x}$ Thin Films

Thickness oscillations of the transport properties in n-type Bi2Te3 topological insulator thin films

We theoretically predict that a large variety of Dirac-cone materials can be constructed in Bi${}_{1-x}$Sb${}_{x}$ thin films, and we here show how to construct single-, bi- and tri- Dirac-cone materials with various amounts of wave vector anisotropy. These different types of Dirac cones can be of special interest to electronic devices design, quantum electrodynamics and other fields.

Constructing a Large Variety of Dirac-Cone Materials in the Bi${}_{1-x}$Sb${}_{x}$ Thin Film System

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Shuang Tang

Author Tools

Chat about Author