Transport Properties For Carbon Nanotubes Under Hydrostatic Pressure
F. Chen, Y. Y. Xue, C. W. Chu, K. L. Stokes and H. Wang
University of Houston, US
Keywords: carbon nanotube, high pressure, thermoelectric, transport, Luttinger liquid
Multi-wall carbon nanotubes (MWNTs) were mixed with polystyrene (PS) by 20 wt%,
which is close to the percolation threshold.
Temperature (T) dependence of Seebeck coefficient (S) and resistance (R) for the sample (MWNT-PS) were measured under hydrostatic pressure upto 1.2 GPa. The resistance showed power law behavior versus temperature (R ~ T^alpha) and agreed well with Luttinger liquid (LL) model. The power law coefficient alpha agreed well with the theory prediction for CNT with Coulomb interactions and the experimental data of `bulk-contacted' single-wall carbon nanotube (SWNT).
Alpha increased slightly under high pressure, suggesting enhanced influence of Coulomb interactions under high pressure. This could be due to either increased Coulomb screening radius or reduced Fermi velocity under high pressure. The pressure increased S slightly. The small magnitude and linearity of S versus T showed metallic behavior under all our experimental pressures. The theoretical prediction of pressure-induced metal-insulator transition for SWNTs was not able to be confirmed by this experiment. Experiments on SWNT mixed in polycarbonate (PC) will be conducted to testify the theoretical prediction.
NSTI Nanotech 2003 Conference Technical Program Abstract