Distinct vortex-glass phases in Yb3Rh4Sn13 at high and low magnetic fields

The vortex lattice (VL) in the mixed state of the stannide superconductor Yb3Rh4Sn13 has been studied using small-angle neutron scattering (SANS). The field dependences of the normalized longitudinal and transverse correlation lengths of the VL, ξL/a0 and ξT/a0, reveal two distinct anomalies that are associated with vortex-glass phases below μ0Hl 700 G and above μ0Hh ∼ 1.7 T (a0 is the intervortex distance). At high fields, around 1.7 T, the longitudinal correlation decreases abruptly with increasing fields indicating a weakening (but not a complete destruction) of the VL due to a phase transition into a glassy phase, below (1.8 K) 2.5 T. ξL/a0 and ξT/a0, gradually decrease for decreasing fields of strengths less than 1 T and tend towards zero. The shear elastic modulus c66 and the tilting elastic modulus c44 vanish at a critical field μ0Hl 700 G, providing evidence for a disorder-induced transition into a vortex-glass. A 'ring' of scattered intensity is observed for fields lower than 700 G, i.e. . This low-field phenomenon is of different nature than the one observed at high fields, where ξL/a0 but not ξT/a0, decreases abruptly to an intermediate value.