Anomalous time behaviors of remanent and normal magnetizations in spinel spin glass Ga_(0.8)Fe_(0.2)NiCrO_4

摘要

Complex spin glass behavior is found to be present in a spinel system Ga_(0.8)Fe_(0.2)NiCrO_4 where the cations occupy two different sites, namely the tetrahedrally coordinated A site and the octahedrally coordinated B site. The complex findings include anomalous time (t) variations of isothermal remanent magnetization (IRM), thermoremanent magnetization (TRM), zero field cooled magnetization [M(ZFC)], and field cooled magnetization [M(FC)]. Surprising results, like M(FC) < M(ZFC), M(FC) decreasing and changing faster than a slow increasing M(ZFC) with t, the M(FC), M(ZFC) not moving (i.e., not changing with t) toward a common equilibrium value, M_(eq), and the IRM, TRM increasing with t, also exist for certain H (external magnetic field), T (temperature), t values. We have tried to understand the above and other observed results on the basis of the possible separate time behaviors of the A- and B-site magnetizations in the system.