Mechanism of grain-boundary magnetoresistance in Fe3O4 films M. Ziese, R. Höhne, H. C. Semmelhack, H. Reckentin, N. H. Hong and P. Esquinazi Eur. Phys. J. B, 28 4 (2002) 415-422 Published online: 13 August 2002 DOI: 10.1140/epjb/e2002-00245-3