Superconducting Molecular Electronics and Molecular Spintronics
Development of Superconducting and Magnetic Molecular Devices Based on Carbon Nanotubes and DNA Molecules
Tech Area / Field
- INF-ELE/Microelectronics and Optoelectronics/Information and Communications
- MAT-SYN/Materials Synthesis and Processing/Materials
3 Approved without Funding
Institute of Microelectronics Technology and High Purity Materials, Russia, Moscow reg., Chernogolovka
- Institute of Bioorganic Chemistry, Russia, Moscow\nVNIIEF, Russia, N. Novgorod reg., Sarov\nMISIS (Steel and Alloys), Russia, Moscow
- Instituto de Estructura de la Materia, Spain, Madrid\nInstitute of Physical and Chemical Research (RIKEN), Japan, Saitama, Wako\nVirginia Polytechnic Institute and State University / College of Arts and Sciences, USA, VA, Blacksburg\nURA 0073/Universite Paris-Sud / Laboratoire de Physique des Solides, France, Orsay
Project summaryThe purpose of this project is creation of new directions in molecular electronics: superconducting molecular electronics and molecular spintronics. The basic devices of these directions will be controllable junctions: superconductor-molecule-superconductor (SMS) and ferromagnet-molecule-ferromagnet (FMF) with carbon nanotubes and DNAs as molecules. We will fabricate the junctions, study their transport properties and characterize them by observation using high resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS).
Very important part of the project will be the characterization of charge carriers in molecules. That is the checking of the possibility of fractional charge in molecular wires. For this we will study Aharonov-Bohm effect in single-walled carbon nanotubes in magnetic fields up to 2,800 T.
Atomic resolution visualization and atomic resolution spectroscopy of fabricated devices are key elements of this project. These methods are fundamental to aid the transition of molecular electronics from the region of basic science to the region of technology. HRTEM is much more powerful than the standard AFM visualization method used by most other groups in the world since internal structures of molecules and even exact number of molecules between electrodes remain always unknown. We have developed a sample mounting procedure where suspended inpidual molecules are soldered to metallic pads on both sides of a slit. This technique enables precise characterization of the samples by HRTEM. It is also possible to use the electron beam to modify the structure under the microscope, simultaneously monitoring its resistance.
We will use different types of (1) carbon nanotubes and (2) DNAs:
1 Single walled carbon nanotubes (SWNT) and small ropes grown by laser ablation or arc method; SWNTs and double walled carbon nanotubes grown by different CVD methods; SWNTs filled by fullerene molecules with magnetic atoms inside-doped "peapods".
2. Standard double-stranded (ds) lambda DNAs; dsDNAs with ordered base pairs structure; dsDNAs doped by heavy (U, Th) and magnetic (Eu, La) atoms; quadruplex DNAs - "G-wires".
We plan to create 3 types of devices from these molecules:
– Superconducting Kondo-effect transistor; electric field on the gate will change the state of a molecule in SMS junction between odd and even numbers of electrons. The behavior of such a device is expected to result from the competition between Kondo effect and superconductivity.
– "Kondo-chain" device will represent junction with a molecule doped by magnetic atoms; transparency of a molecule for conduction electrons will be changed by magnetic field.
– FMF junction with controllable magnetization direction of ferromagnetic electrodes; ferromagnetic electrodes will be included in 2 independent electrical nanocircuits with spin-polarized current.
The final aim of this project – fabrication, visualization and study of transport properties of sub-10nm molecular devices is very important for molecular electronics. One essential point of this project is the possibility to have a precise visualization of the molecular device we are measuring, in contrast with most studied sub-10nm devices, where many details of device structure including molecules between electrodes remained "invisible".
The basic fundamental problem of the project is the study of superconducting and spin carrier in quasi-unidimensional molecular wires representing Lattinger liquid of strongly interacting electrons. This area of study of electron transport in molecules is least investigated. The participants and сollaborators of the project have discovered superconductivity and spin transport in molecular wires (Kasumov et.al. Science 284, 1508 (1999); Science 291, 280 (2001); Tsukagoshi et.al. Nature 401, 572 (1999)), and are the world leaders in this field.
The most interesting consequence of a strong interaction of electrons is the renormalization of their charge leading to an appearance of carriers with the fractional charge. The opportunity of observation of similar carriers in molecular wires (for example, in carbon nanotubes) is a subject of numerous discussions.
This project is the first one to propose a direct experiment for the solution of this problem: examination of Aharonov-Bohm effect in singlewalled carbon nanotubes. The enormous magnetic fields (up to 2800 T), necessary for this experiment, will be generated using the unique facility in VNIEF, Sarov. There are no other such facilities in the world.
VNIEF is one of the main developers of nuclear weapons in Russia. Involving scientists of this institute in the basic research project, obeys the fundamental objectives of ISTC. The participation of these scientists in the project is essential. It is necessary for the acquirement of the most significant fundamental result of the project.
Apart from unique VNIEF facility, the participants of the project have all the necessary equipment for fabrication and study of molecular devices: ion beam machine able to produce ion beam of downto 100 nm in diameter; scanning transmission electron microscope VG HB501 for carbon nanostructures fabrication and nanolithography; transmission electron microscopes JEOL JEM-2000FX and JEM-100CX for visual observation of the structures being prepared; high purity metals, necessary for thin film deposition; thin film deposition machines using partially ionized flow and magnetron sputtering methods; dilution fridge for low temperature electron transport measurements.
Part of investigations will be carried out using collaborators equipment. The transport measurements at vert low temperatures (down to 15 mK) and EELS spectroscopy will be carried out in LPS (France). A part of transport measurements and sub 10 nm electron-beam lithography will be carried out in RIKEN (Japan).
The cooperation of head institute of the project on studying molecular nanostructures with French collaborators from LPS lasts already for about 8 years. The cooperation with the scientists from RIKEN began this year. Such steady-stated cooperation significantly facilitates the work on the project.
The present project has interdisciplinary character and combines the participants, which are the experts in different areas of science and technologies: IMT – nanophysics, nanotechnology; MISiS – material science; VNIEF – physics and technology of superstrong magnetic fields; IBCh – biology, biotechnology. The purpose of this integration is creation of new directions in Information Technology: superconducting molecular electronics and molecular spintronics.
The main goal of molecular electronics is creation of molecular computer with very high density of devices - order of a thousand billions per centimeter square. This giant density demands extremely low power dissipation per one working device. We believe that only superconducting or spin-effect based devices can satisfy this demand.
The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.
ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.