Change in blocking temperature of nanoparticle array deposited on magnetoresistive sensor

Here we present the effect of ferromagnetic magnetoresistive sensor on magnetic susceptibility of nanoparticles (NPs) deposited on its surface. Deposition of the CoFe2O4 nanoparticles on the CoFeB/Ta/CoFeB platform, comprising thin ferromagnetic layers, changes the blocking temperature of the NPs. The magnetic dipole interaction between the NPs and the platform affects the frequency and field dependences of the blocking temperature of the NPs, because the effective energy barrier of magnetization reversal is higher than in NPs deposited on a diamagnetic substrate. Obtained results demonstrate backward effect of the sensor on the analyzing NPs array. An allowance of this effect is important for the correct application of a magnetoresistive and low frequency inductive sensors in medicine and biology.

Automated summary

The effect of a ferromagnetic magnetoresistive sensor on the magnetic susceptibility of nanoparticles (NPs) deposited on its surface is presented in this study. It is found that the deposition of CoFe2O4 nanoparticles on a CoFeB/Ta/CoFeB platform, consisting of thin ferromagnetic layers, changes the blocking temperature of the NPs. This change in temperature is attributed to the magnetic dipole interaction between the NPs and the platform, which affects the frequency and field dependences of the NPs' blocking temperature. The results obtained demonstrate the importance of considering the backward effect of the sensor for the correct application of magnetoresistive and low-frequency inductive sensors in medicine and biology.