Unveiling of Bragg glass to vortex glass transition by an ac driving force in a single crystal of Yb3Rh4Sn13

We present here some striking discrepancies in the results of ac and dc magnetization measurements performed in a single crystal of a low-T-c superconductor, Yb3Rh4Sn13. The fingerprint of a transition from an ordered vortex lattice a la Bragg glass (BG) phase to a partially disordered vortex glass (VG)-like phase is unearthed under the influence of an ac driving force present inevitably in the isothermal ac susceptibility (chi'(H)) measurements. In contrast to its well-known effect of improving the state of spatial order in the vortex matter, the ac drive is surprisingly found to promote disorder by helping the BG-to-VG transition to occur at a lower field value in this compound. On the other hand, the isothermal dc magnetization (M-H) scans, devoid of such a driving force, do not reveal this transition; they instead yield the signature of another order-disorder transition at elevated fields, i.e., peak effect (PE), located substantially above the BG-to-VG transition observed in chi' (H) runs. Further, the evolution of the PE feature with increasing field as observed in isofield ac susceptibility (chi' (T)) plots indicates the emergence of an ordered vortex configuration (BG) from a disordered phase above a certain field, H* (similar to 4 kOe). Below H*, the vortex matter created via field cooling (FC) is found to be better spatially ordered than that prepared in zero field-cooled (ZFC) mode. This is contrary to the usual behavior anticipated near the high-field order-disorder transition (PE), wherein an FC state is supposed to be a supercooled disordered phase and the ZFC state is comparatively better ordered