We report observation of coherent quantum oscilations in spin-10 Fe8 molecular clusters. The powder of magnetically oriented Fe8 crystallites was placed inside a resonator, in a dc magnetic field perpendicular to the magnetization axis. The field dependence of the ac-susceptibility was measured up to 5 T, at 680 MHz, down to 25 mK. Two peaks in the imaginary part of the susceptibility have been...

The ac susceptibility of single crystalline tetragonal EuFe2As2, EuFe2As1.4P0.6, and EuFe1.715Co0.285As2 has been measured over the temperature and hydrostatic (He-gas) pressure ranges 10–60 K and 0–0.8 GPa, respectively. For all three samples the magnetic ordering temperature (17–19 K) from the Eu sublattice increases linearly with pressure, presumably due to the enhanced exchange coupling bet...

Discontinuous magnetic multilayers [Co80Fe20(t)/Al2O3(3nm)]10 with t = 0.9 and 1.0nm are studied by SQUID magnetometry and ac susceptibility. Owing to dipolar interaction the superparamagnetic cluster systems undergo collective glass-like freezing upon cooling. While both samples exhibit very similar glass temperatures Tg ≈ 45 K and critical exponents zν ≈ 10 and γ ≈ 1.4 as obtained from the te...

The analysis of ac magnetic susceptibility data has shown that mechanically alloyed Fe30Ag40W30 , a highly heterogeneous nanogranular system, exhibits critical dynamics in its transition to a low-temperature spin-glasslike phase, as proved by the power-law divergence of the relaxation time at Tg519.7 K, and by the dynamic scaling behavior of the out-of-phase component of the susceptibility. Bot...