MAGNETIC-FIELD-INDUCED GRIFFITHS PHASE VERSUS RANDOM-FIELD CRITICALITY AND DOMAIN-WALL SUSCEPTIBILITY OF FE0.47ZN0.53F2

The well-known peak of the parallel ac susceptibility arising below T-N in Fe0.47Zn0.53F2 splits into a narrow critical peak at T-c(H) and a broad field-induced Griffiths phase shoulder peaking at T-p > T-c(H) in magnetic fields H equal to or greater than 1.6 MA/m. Random-field (RF) criticality with and alpha approximate to 0 and subsequent rounding due to RF trapping of thermal fluctuations are observed upon zero-field cooling as T --> T-c(-)(H). The frozen domain state obtained after rapid field cooling reveals excess susceptibility Delta chi(w)(l) proportional to H-2.6, owing to rough walls with thermally activated stiffness.