Electric-field-induced macroscopic asymmetry in blue bronzeK0.3MoO3

The hysteresis in the current-voltage characteristics, observed previously in several charge-density-wave compounds, was investigated in blue bronze (${\mathrm{K}}_{0.3}$ ${\mathrm{MoO}}_3$) at 77 K. We found that currents close to or above the threshold current for the nonlinear conduction induce asymmetric changes in the low-field resistance of the sample: While the resistance increases where the current enters, it decreases in the other half of the sample. The relationship of our findings to the recent observations of macroscopic polarization and metastable states is discussed.