Nguyen Ngoc Viet

Synthesis and Electrical Transport of Ultra-clean Carbon Nanotubes: Strong Spin-orbit Coupling in Kondo Regime Nguyen Ngoc Viet

This book describes experiments on the synthesis of single wall carbon nanotubes (SWNTs), fabrication of ultraclean CNT devices, and study of electronic properties of CNTs with transport measurements. The first part of this work describes the optimization of the synthesis parameters (by chemical vapor deposition - CVD) such as carbon precursors, gas flows, temperature, catalyst for the growth of high quality SWNTs. In all these parameters, the catalyst composition plays a very important role on the high selective growth of SWNTs with a narrow diameter distribution. The second part deals with the nanofabrication of ultra-clean CNT devices and the low temperature (40 mK) transport measurements of these CNT quantum dots. The level spectra of the electrons in the first shell are investigated using inelastic cotunneling spectroscopy in an axial magnetic field, which show a strong negative spin-orbit coupling of electron. We find that the sequence of electron shell filling in our case (?SO < 0) is different from which would be obtained in the pure SU(4) Kondo regime (?SO = 0). Indeed, a pure orbital Kondo effect is observed in N=2e at a finite magnetic field.