Successive spin glass, cluster ferromagnetic, and superparamagnetic transitions in RuSr _2Y _(1.5)Ce _(0.5)Cu _2O10 complex magneto-superconductor

摘要

We report structural, DC magnetization, detailed linearon-linear AC susceptibility, (with applied frequency and amplitude) isothermal and thermoremanent magnetization (TRM) behavior for RuSr _2Y _(1.5)Ce _(0.5)Cu _2O10 (YRu-1222) magneto- superconductor to understand its complex magnetism. Studied sample is synthesized through the novel solid state high pressure (6 GPa) high temperature (1450°C) (HPHT) technique. The compound is crystallized in tetragonal structure with space group I4/mmm (No. 139). DC magnetic susceptibility shows that studied YRu-1222 is magneto-superconducting with Ru spins magnetic ordering at around 110 K and superconductivity (SC) in the Cu-O2 planes below 30 K. Frequency and field dependent detailed AC magnetic susceptibility measurements confirms the spin-glass (SG) behavior with homogeneouson-homogeneous ferromagnetic (FM) clusters in this system. Variation of cusp position with applied AC frequency follows the famous Vogel-Fulcher law, which is commonly accepted feature for spin-glass (SG) system with homogeneouson-homogeneous ferromagnetic clusters embedded in spin-glass (SG) matrix. Above the freezing temperature (Tf), first and third harmonics AC susceptibility analysis indicated possibility of the co-existence of spin cluster ferromagnetism with superparamagnetism (SPM). The M-H loops at low temperature exhibit the ferromagnetic behavior with rather small coercive field (Hc) and remnant magnetization (Mr). Summarily, the magnetic (DC and AC) susceptibility measurements and their analysis have enabled us to unearth the complex magnetism in terms of successive SG-FM-SPM transitions with temperature.