X-ray diffraction study on YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 superlattices with thinner YBCO layers

with increase of the thickness of the PrBCO layer in superlattices with thin YBCO layer, which has been observed by many groups. Several theoretical models have been proposed to account for this interesting phenomenon, including a spin polaron model,