Sliding and quantum interference of charge-density waves moving through columnar defects in NbSe3

We have studied the influence of columnar defects (CD's) on transport and m agnetotransport of NbSe3 in the charge-density wave (CDW) sliding regime. C D's are introduced by irradiation with fast heavy ions (Xe, U, Ph). We show that the CDW motion remains coherent in the whole volume of the sample for a CD concentration less than 10(10) def/cm(2), as demonstrated by complete mode locking experiments. In this defect concentration range, we report on detailed studies of magneto-oscillations of the CDW conduction with a phi( 0)/2 period (phi(0)=hc/e). We show that only the H component parallel to th e CD axes intervenes in magnetoresistance oscillations. The phi(0)/2 period is in good agreement with the diameter of the CD's measured by transmissio n electron microscopy. We attribute magnetoresistance oscillations to the q uantum interference (Aharanov-Bohm effect) of the CDW moving through CD's c ontaining magnetic flux. [S0163-1829(99)09943-9].