Fermi surface and order parameter driven vortex lattice structure transitions in twin-free YBa2Cu3O7.
We report on small-angle neutron scattering studies of the intrinsic vortex lattice (VL) structure in detwinned YBa2Cu3O7 at 2 K, and in fields up to 10.8 T. Because of the suppressed pinning to twin-domain boundaries, a new distorted hexagonal VL structure phase is stabilized at intermediate fields. It is separated from a low-field hexagonal phase of different orientation and distortion by a first-order transition at 2.0(2) T that is probably driven by Fermi surface effects. We argue that another first-order transition at 6.7(2) T, into a rhombic structure with a distortion of opposite sign, marks a crossover from a regime where Fermi surface anisotropy is dominant, to one where the VL structure and distortion is controlled by the order-parameter anisotropy.
White
J S
JS
School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.
Hinkov
V
V
Heslop
R W
RW
Lycett
R J
RJ
Forgan
E M
EM
Bowell
C
C
Strässle
S
S
Abrahamsen
A B
AB
Laver
M
M
Dewhurst
C D
CD
Kohlbrecher
J
J
Gavilano
J L
JL
Mesot
J
J
Keimer
B
B
Erb
A
A