Electron electron interaction in multiwall carbon nanotubes

The magnetic susceptibility χ of pristine and brominated arc-produced sample of multiwall carbon nanotubes was measured from 4.2 to 400 K. An additional contribution Δ χ( T) to diamagnetic susceptibility χ( T) of carbon nanotubes was found at T<50 K for both samples. It is shown that Δ χ( T) are dominated by quantum correction to χ for interaction electrons (interaction effects-IE). The IE shows a crossover from two-dimensional to three-dimensional at B=5.5 T. The effective interaction between electrons for interior layers of nanotubes has been found to be repulsive and the electron-electron interaction λ_c was estimated to be λ_c∼0.26.