The magnetization, pinning force and magnetic relaxation of twinned and de-twinned crystals was studied. A double peak feature appeared in the magnetization curves of crystals having one type of twin boundary in only one direction, whereas a single peak was observed in crystals which were either without twins or with micro-twins or mixed twins in both directions. The double peaks disappeared when the magnetic field was tilted away from the c-axis of the crystal; thus removing the influence of twin boundaries. In the high-field region, the relaxation rate in twinned crystals was small due to the suppression of thermal fluctuations by the presence of twin boundaries.

Influence of Twin Boundaries on the Flux Pinning in NdBa2Cu3Oy Single Crystals. A.K.Pradhan, K.Kuroda, B.Chen, N.Koshizuka: Physical Review B, 1998, 58[14], 9498-503