TY - JOUR TI - Small angle neutron scattering-studies of the vortex lattice in the UPt3 mixed state: Direct structural evidence for the B ? C transition N1 - © 1997 The American Physical Society ID - discovery292011 Y1 - 1997/04/21/ UR - http://dx.doi.org/10.1103/PhysRevLett.78.3185 JF - Physical Review Letters VL - 78 SP - 3185 EP - 3188 A1 - Yaron, U A1 - Gammel, PL A1 - Boebinger, GS A1 - Aeppli, G A1 - Schiffer, P A1 - Bucher, E A1 - Bishop, DJ A1 - Broholm, C A1 - Mortensen, K SN - 0031-9007 N2 - Small angle neutron scattering studies of the flux line lattice (FLL) in UPt3 for fields H?c provide direct microscopic evidence for the 5 kOe B?C transition. We find a pronounced maximum in the longitudinal correlation length of the FLL at the transition and an abrupt change in the field dependence of the scattered intensity which can be interpreted as a 15% decrease in the coherence length and a 9% increase in the penetration depth, consistent with discontinuities in the critical fields. Finally, in the low field phase, the FLL distortion evolves roughly linearly with field, while in the high field phase it appears to be less field dependent. AV - public IS - 16 ER -