Effect of contact with a metal surface on magnetic relaxation in monomolecular magnets in zero magnetic field

The appearance of relaxation maxima on the frequency dependence of magnetic susceptibility was discovered when ferromagnetic demagnetized microparticles of the PrDyFeCoB metal alloy were mixed with an erbium-based molecular magnet complex. At 2 K, ferromagnetic metal microparticles, as well as molecular complexes, did not exhibit magnetic relaxation in the frequency range of 0.1–1400 Hz, accessible to the SQUID magnetometer. In a pressed mixture of a composite material made from these components, the magnetic relaxation signal has a maximum at $\sim$1 kHz. X-ray photoelectron spectroscopy (XPS) of the composite material and comparison of the XPS spectra with the spectra of the initial components of the composite showed that the 10-coordinated complex is oxidized to 8-coordinated as a result of contact with the surface of demagnetized metal microspheres.