Anomalous behavior of the angular-dependent magnetic relaxation in single-crystalBi2Sr2CaCu2Oy

Relaxation of the longitudinal and transverse components of the remanent magnetic moment of single-crystal ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_{\mathit{y}}$ has been investigated as a function of angle. When the angle between the applied field and the c axis is not too large, the remanent moment quickly aligns with the c axis. At extremely high angles the alignment is slow, and at low temperatures the transverse magnetization even increases with time. The temperature dependence of the normalized relaxation rate exhibits two peaks, suggesting the existence of two separate pinning mechanisms.