  We present here some striking discrepancies in the results of ac and dc
magnetization measurements performed in a single crystal of low Tc
superconductor, Yb3Rh4Sn13. Fingerprint of a transition from an ordered vortex
lattice a la Bragg glass (BG) phase to a partially-disordered vortex glass (VG)
like phase gets unearthed under the influence of an ac driving force present
inevitably in the isothermal ac susceptibility 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 assisting 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 signature of another
order-disorder transition at elevated fields, viz., peak effect (PE), located
substantially above the BG to VG transition observed in the isothermal ac
susceptibility measurements. Further, the evolution of PE feature with
increasing field as observed in isofield ac susceptibility plots indicates
emergence of an ordered vortex configuration (BG) from a disordered phase above
a certain field, H* (~ 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 a FC
state is supposed to be a supercooled disordered phase and the ZFC state is
comparatively better ordered.
