Macroscopic quantum coherence in charge density wave whisker NbSe3 under strain

The magnetoresistance oscillation of the charge density wave (CDW) material NbSe3 whisker has been studied under strain at different temperatures (4.2 K, 30 K, 40 K). With a constant measuring current, the magnetoresistance ( MR) curves oscillate at 30 K while they are smooth at 4.2 K and become a se ries of zigzag curves at 40 K. These oscillation periods are Delta H, rathe r than Delta(1/H). It is found that either increasing the temperature to 40 K, or straining the sample to a displacement as large as epsilon = 3.1%, m akes the regular oscillations disappear. By analysing the data, we found ou r results can be interpreted as the quantum coherence effect of a moving CD W.