CONDUCTIVITY AND INDUCED SUPERCONDUCTIVITY IN DNA

Transcription

1 CONDUCTIVITY AND INDUCED SUPERCONDUCTIVITY IN DNA A.Yu. Kasumov 1,2, K.Tsukagoshi 1,3, M. Kawamura 1, T. Kobayashi 1, Y.Aoyagi 1,4, V.T. Volkov 2, Yu.A. Kasumov 2, D.V. Klinov 5, M. Kociak 6, P.-E. Roche 6, R. Deblock 6, S. Guéron 6, H. Bouchiat 6 1. RIKEN, Hirosawa 2-1, Wako, Saitama , Japan. 2. Institute of Microelectronics Technology RAS, Chernogolovka, Moscow district, , Russia. 3. PRESTO, JST, Honcho 4-1-8, Kawaguchi, Saitama, Japan. 4. Department of Information Processing, Tokyo Institute of Technology, Nagatsuda 4259, Midori, Yokohama, Kanagawa , Japan. 5. Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, RAS, Miklukho-Maklaya 16/10, Moscow , Russia. 6. Laboratoire de Physique des Solides UMR Universite Paris-Sud, Bat. 510, Orsay cedex, France.

2 Limits for Molecular Electronics Lg(P), P - power [W] Q=50 W/cm 2 - maxheat removal Heisenberg principle N=10 12 /cm 2 - density of devices restriction: E min = h / t d Pentium transistor Allowed region for molecular electronics Nanotube transistor (IBM) Josephson transistor Q/Np=50 W Von Neuman restriction: E min = (ln2)kt, T = 300 K Limit for room temperature molecular electronics lg(t d ), t d - delay [s] neuron

3 Schematic picture of compressed DNA Transmission electron microscopy image of Pt/C DNA replica from untreated mica shadowed at 6 degrees, indicating a thickness of 1nm. Kasumov et al., APL, 2004

4 AFM (left) and SRM (right) pictures of DNA molecules DNAs - INSULATORS! without pentylamine treatment DNAs - CONDUCTORS! with pentylamine treatment Individual DNA and a rope of DNAs combed across the slit profiles of DNAs current scales of SRM (voltage was up to 0.23 V)

5 Combing of DNA molecules Two leveled plastic tubes connected to outlets of a peristaltic pump (in order to control the flowing rate) are fixed in the sample holder touching the surface of a sample. The flowing DNA solution is running out from one tube into the other with a velocity of the order of 1-2 cm/sec

6 Scaling behavior of the differential resistance in the temperature range between 0.1 K and 1 K and voltage range between 0.02 and 0.4 mv. The reason for the conducivity is long range correlations in structure of DNA; Carpena et al., Nature, 2002 Bias dependence of the differential resistance for different temperatures between 0.1 and 1K. Note the asymmetry of the curves above 0.4 mv. The excitation current is 0.1 na. Low temperature conductivity of DNAs

7 DNA molecules between metallic electrodes DNA molecules aligned by solution flow on Re-C electrodes separated by 500 nm gap deposited on mica substrate AFM image of molecules on contacts Molecules between contacts λ-dna Mica Bilayer Re/C superconductor with Tc=1 K Pt electrodes Some essential points: Surface preparation (height of molecules = 2nm) Height of electrodes (no more than 3 nm) DNA molecules prepared in this way have resistances ~100 kω per molecule. Treatment by enzymes suppresses DNAs conductivity completely!

8 Proximity induced superconductivity in DNA molecules Contacts Re/C Tc ~ 1K Nomber of molecules between contacts ~ 10 Linear transport : Resistance drop at T<Tc Disappears in magnetic field Kasumov et al. Science 2001 Electron pairs may penetrate into DNA with length of the order of 1 micron which demonstrate the coherent character of the transport.

9 Non-linear Transport in DNAs 25? 0 H=0.8 T dv/di (k? ) dv/di (k? ) dv/di (k? ) DNA1 DNA2 DNA3? 0 H=0 T? 0 H=0.9 T? 0 H=0 T? 0 H=0 T? 0 H=1 T -1,0-0,5 0,0 0,5 1,0 V (mv) Voltage dependence of the differential resistance measured at 50 mk in magnetic fields of 0, 0.2, 0.4, 0.6, 0.8, and 1 T for 3 DNA samples. These measurements were done with an ac excitation current of 1 na at 30 Hz.

10 Conclusions DNA is conductive in the case of native thickness only! Proximity induced superconductivity in DNA is due to long range coherent transport

11 Perspective Fabrication and Study of sub-10nm Gate Controlled Molecular Josephson Junction Gate DNA molecule 1-5 nm Superconductor Superconductor

12 Deposition and TEM image of metallofullerens Actual HRTEM image of sample Gd1 82 molecular dimer between electrodes). Schematic picture of the molecular dimer between superconducting electrodes. The red dots symbolize the Gd atoms inside the fullerene cage. Sketch representing the metallofullerene molecules deposition.