Strong Flux Pinning by Magnetic Interlayers Compatible With ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$
A multilayer thin film comprising pure YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> (YBCO) interlayered with heavily YFeO<sub>3</sub>- doped YBCO has been fabricated on a vicinal-cut SrTiO<sub>3</sub> substrate, thereby separating geometrically the contributions of the intrinsic flux pinning due to the YBCO <i>ab</i> planes and the pinning due to the magnetically-doped interlayers. It is consequently found that the magnetic planes provide flux pinning of a strength comparable to the intrinsic pinning in YBCO at low fields, highlighting the efficacy of YFeO<sub>3</sub> as a magnetic pinning additive for YBCO, and emphasizing that in contrast to pinning by normal-state material, pinning by magnetic material is strongest at low applied fields.