Search

Magnetization studies have been performed on a polycrystalline sample of Dy5Si3Ge as a function of an applied magnetic field (up to 50 kOe) and hydrostatic pressure (up to 10 kbar) in the 5-300 K temperature range. The anomalous behavior of the magnetic susceptibility indicates that a Griffiths-like phase exists at low magnetic fields and pressures up to 10 kbar. We present evidence that the high-temperature second-order ferromagnetic transition can be coupled with the low-temperature first-order crystallographic transformation into a single first-order magnetic-crystallographic transformation using a magnetic field and hydrostatic pressure as tuning parameters. The effect of pressure on the Griffiths-like phase is reported and analyzed in the framework of the complex competition between the interslab and intraslab magnetic interactions. [ABSTRACT FROM AUTHOR]

Abstract: Muon spin relaxation measurements have been performed over the wide temperature range from 0.4 to 200K in some representative compositions where a cluster-glass phase at temperatures above the ferromagnetic ground state has been characterized by AC–DC magnetization measurements. The analysis of these data reveals the presence of a highly inhomogeneous magnetic state at temperatures above the freezing temperature (seen by AC susceptibility) that runs into the paramagnetic regime. This inhomogeneous magnetic state consists of long-range ordered and non-ordered fractions, the latter increasing with temperature. An unusual strong dependence of the magnetic response on magnetic field history such as zero field cooling vs. field cooling within the intermediate magnetically inhomogeneous range is found. The present analysis considering also previous neutron scattering, magnetic characterization, specific heat allows us to present a complete description of the system. We propose that the long-range magnetic order at low temperature is achieved by a percolative process of magnetic clusters that become static below . [Copyright &y& Elsevier]

Abstract: Temperature-dependent zero-, longitudinal- and transverse-field spectra have been recorded in nanometric obtained by mechanical alloying. The alloy comprises Fe(Cu) nanoparticles (5nm) in a Ag matrix formed by 16nm particles, as deduced from the Rietveld refinement of the X-ray diffraction pattern. The muon depolarization can be described by a Dynamical Lorentzian Kubo–Toyabe function. This is in agreement with a high degree of interparticle dipolar interactions, giving rise to a cluster spin glass-like behavior below 100K. The intra particle interactions are also probed by the , and influence the thermal variation of the static width. [Copyright &y& Elsevier]