Eskildsen, M. R.Gammel, P. L.Barber, B. P.Yaron, U.Ramirez, A. P.Huse, D. A.Bishop, D. J.Bolle, C.Lieber, C. M.Oxx, S.2019-09-271997Eskildsen, M. R., P. L. Gammel, B. P. Barber, U. Yaron, A. P. Ramirez, D. A. Huse, D. J. Bishop, et al. 1997. “Observation of a Field-Driven Structural Phase Transition in the Flux Line Lattice in ErNi 2 B 2 C.” Physical Review Letters 78 (10): 1968–71. https://doi.org/10.1103/physrevlett.78.1968.0031-90071079-71141092-0145http://nrs.harvard.edu/urn-3:HUL.InstRepos:41417269Small-angle neutron scattering and magnetic decoration both demonstrate a topological transition in the flux line lattice (FLL) in ErNi2B2C. The high-field square lattice slowly transforms into a hexagonal lattice via an area preserving [100] rhombohedral distortion below roughly 500 Oe. The square FLL is aligned with the [110] direction of the tetragonal crystal, while the two domains of the hexagonal FLL are aligned with [100] and [010]. The differences in pinning for the two FLL topologies are reflected in the rf kinetic inductance.en-USJournal Article2019-09-2710.1103/PhysRevLett.78.1968