Anomalous thickness-dependent exchange bias effect in Fe3O4/YMnO3 multiferroic heterostructures Dongxing Zheng, Mingyu Sun, Dong Li, Peng Li, Chao Jin and Haili Bai EPL, 110 2 (2015) 27005 Published online: 06 May 2015 DOI: 10.1209/0295-5075/110/27005