Changes in hysteretic behavior of PMA thin films due to the interaction with CoFe2O4 nanoparticles: A new way for magnetic sensing

S. Michea, R. Melo Freire, J.L. Palma , J. C. Denardin, D. ALtbir
Universidad Autonoma de CHile,

Keywords: nanoparticles, thin films, magnetic sensor


In this work, changes in hysteretic behavior for magnetic multilayer thin films with perpendicular magnetic anisotropy (PMA) under the influence of superparamagnetic nanoparticles are presented. Firstly, Si/[Pd(1.5nm)Co(0.3nm)]x10/Pd(2nm) magnetic thin films were fabricated by sputtering machine over silicon substrate. Subsequently, CoFe2O4 nanoparticles (nps) were prepared using a stainless-steel reaction kettle with a Teflon-liner (20 ml) and were dispersed in hexane and stored at 4°C for further characterization and use. The magnetic characterization was carried out using an Alternate Gradient Force magnetometer. For the magnetic film it is possible to observe the typical square behavior for thin film whit PMA. With 118 ug (each 10ul) of nps over thin magnetic film, we observe a complete change in the magnetic behavior in both, remnant magnetization and coercivity. It is also possible to note a waist in the loop, which may be due to a chiral reversion process in film induced by the interaction with nps. The gorgeous change in the main features of the hysteresis loop generates a great possibility of novel applications.