Imaging field-dependent structure in charge-density waves by X-ray diffraction topography

We have imaged field-dependent CDW structure in NbSe3 single crystals by X- ray diffraction topography. Just above E-T, the CDW shears along longitudin al steps in crystal thickness associated with small-angle grain boundaries, and at high fields transverse correlations recover. These results demonstr ate X-ray topography as an effective probe of CDW structure, and together w ith earlier transport measurements establish that extrinsic sources dominat e the most obvious manifestations of plasticity in this CDW conductor.