Resumen: Herein we present the results of specific loss power (SLP) analysis of polydisperse water based ferrofluids, Fe3O4/PEG200 and Fe3O4/PEG6000, with average Fe3O4 particle size of 9¿nm and 11¿nm, respectively. Specific loss power was measured in alternating magnetic field of various amplitudes and at fixed frequency of 580.5¿kHz. Maximum SLP values acquired were 195¿W/g for Fe3O4/PEG200 and 60¿W/g for Fe3O4/PEG6000 samples. The samples were labeled as superparamagnetic by magnetization measurements, but SLP field dependence showed deviation from the behavior predicted by the commonly employed linear response theory. The scope of this theory for both samples with wide particle size distribution is discussed. Deviation from the expected behavior is explained by referring to polydisperse nature of the samples and field dependent relaxation rates. Idioma: Inglés DOI: 10.1063/1.4914074 Año: 2015 Publicado en: Journal of Applied Physics 117, 10 (2015), 103903 [6 pp] ISSN: 0021-8979 Factor impacto JCR: 2.101 (2015) Categ. JCR: PHYSICS, APPLIED rank: 47 / 145 = 0.324 (2015) - Q2 - T1 Factor impacto SCIMAGO: 0.821 - Physics and Astronomy (miscellaneous) (Q2)