Magnetic disorder in nanoparticles: from an old drawback to a tailorable strategy

Engineering magnetic defects has become, in the last years, a revolutionary material design strategy. Harnessed in technological applications, such as data storage, or investigated for expanding the limits of knowledge, magnetic disorder has opened a new room in the field of nanomagnetism. However, in nanoparticles, the full potential of spin disorder is yet to be fully unlocked. The field misses the adequate methodology, the theoretical basis and experiemental methods to be used as a scaffold on which to build such a new paradigm. In this talk, I will present key results from my current MSCA-YIA project, named HYPUSH, which aims to harness intra-particle magnetic inhomogeneities for pushing the therapeutic efficiency of magnetic hyperthermia. With a strong emphasis on micromagnetic calculations, HYPUSH combines real-space calculations with small-angle neutron scattering to establish a correlation between structural features and spin arrangement, resolve heat dissipation at the nanometer scale, and provide predictive macroscopic heating metrics.

In this talk, I will focus on maghemite nanoflowers, excellent nanotransducers in magnetic hyperthermia, for which the influence of intra-particle disorder on the magnetization reversal and associated heat release has remained so far elusive. Using micromagnetic simulations reproducing their particular morphology, this talk will show the emergence of non-homogeneous intra-particle spin textures, identifying further the location of intra-particle “hot-spots”. This numerical study provides a solid foundation for optimized nanoparticle designs including magnetic disorder as a tailorable parameter for enhanced macroscopic performance.