Strain-induced bi-thermoelectricity in tapered carbon nanotubes

We show that carbon-based nanostructured materials are a novel testbed for controlling thermoelectricity and have the potential to underpin the development of new cost-effective environmentally-friendly thermoelectric materials. In single-molecule junctions, it is known that transport resonances associated with the discrete molecular levels play a key role in the thermoelectric performance, but such resonances have not been exploited in carbon nanotubes (CNTs). Here we study junctions formed from tapered CNTs and demonstrate that such structures possess transport resonances near the Fermi level, whose energetic location can be varied by applying strain, resulting in an ability to tune the sign of their Seebeck coefficient. These results reveal that tapered CNTs form a new class of bi-thermoelectric materials, exhibiting both positive and negative thermopower. This ability to change the sign of the Seebeck coefficient allows the thermovoltage in carbon-based thermoelectric devices to be boosted by placing CNTs with alternating-sign Seebeck coefficients in tandem

GOLLUM: a next-generation simulation tool for electron, thermal and spin transport

We have developed an efficient simulation tool 'GOLLUM' for the computation of electrical, spin and thermal transport characteristics of complex nanostructures. The new multi-scale, multi-terminal tool addresses a number of new challenges and functionalities that have emerged in nanoscale-scale transport over the past few years. To illustrate the flexibility and functionality of GOLLUM, we present a range of demonstrator calculations encompassing charge, spin and thermal transport, corrections to density functional theory such as LDA+U and spectral adjustments, transport in the presence of non-collinear magnetism, the quantum-Hall effect, Kondo and Coulomb blockade effects, finite-voltage transport, multi-terminal transport, quantum pumps, superconducting nanostructures, environmental effects and pulling curves and conductance histograms for mechanically-controlled-break-junction experiments.Comment: 66 journal pages, 57 figure

Preface

The 1st International Scientific Conference on Pure Science (ISCPS2019) was held on 23 -24 January 2019 at the University of Al-Qadisiyah, College of Education, Diwaniyah, South of Iraq. The ISCPS2019 was the first forum to present the innovative results of the advanced topics in physics, mathematics, biology, and chemistry. The conference was jointly organised by the Ministry of Higher Education and Scientific Research in Iraq. The conference is an opportunity to achieve the strategic goals on the processes of activating the own capability to build (knowledge society), and keep abreast of scientific developments in the fields of science, and their applications and investments to serve the society. Thus, the conference aims is to bring together leading academics, scholars and students to discuss theoretical and practical issues to share their experiences and research findings, as well as ideas, problems and solutions related to the multifaceted aspects of Advanced Science. In this Conference, 300 technical papers were presented by local and international participants. The event included the contributions of large number of researchers, elite of universities and scientific institutions inside and outside Iraq. The contributions focused on the exchange of ideas and the dissemination of scientific knowledge. A number of reviewers assessed the quality of manuscripts. A rigorous peer-review process have implemented to evaluate the manuscripts. All accepted papers will be published in the conference proceeding. A booklet of abstracts was given to all participants on the registration day. The Committee have selected the high-quality manuscripts for publication in a special issue within a recognized international journal (with Clarivate and Scopus Indexing). The organised committee would like to thank the editors, Keynote speakers, reviewers and authors who have contributed to the Conference Proceedings. Our special thanks go to the Iraqi Higher Education and Scientific Research for their support towards the successful organization of the conference