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Title: Magnetic-field-induced vortex-lattice transition in HgBa 2 CuO 4 + δ

Measurements of the 17O nuclear magnetic resonance (NMR) quadrupolar spectrum of apical oxygen in HgBa 2CuO 4+δ were performed over a range of magnetic fields from 6.4–30 T in the superconducting state. Oxygen-isotope-exchanged single crystals were investigated with doping corresponding to superconducting transition temperatures from 74 K underdoped, to 78 K overdoped. The apical oxygen site was chosen since its NMR spectrum has narrow quadrupolar satellites that are well separated from any other resonance. Nonvortex contributions to the spectra can be deconvolved in the time domain to determine the local magnetic field distribution from the vortices. Numerical analysis using Brandt's Ginzburg-Landau theory was used to find structural parameters of the vortex lattice, penetration depth, and coherence length as a function of magnetic field in the vortex solid phase. From this analysis we report a vortex structural transition near 15 T from an oblique lattice with an opening angle of 73° at low magnetic fields to a triangular lattice with 60° stabilized at high field. The temperature for onset of vortex dynamics has been identified from spin-spin relaxation. This is independent of the magnetic field at sufficiently high magnetic field similar to that reported for YBa 2Cu 3O 7 and Bimore » 2Sr 2CaCu 2O 8+δ and is correlated with mass anisotropy of the material. Here, this behavior is accounted for theoretically only in the limit of very high anisotropy.« less
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  1. Northwestern Univ., Evanston, IL (United States)
  2. National High Magnetic Field Lab., Tallahassee, FL (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 2469-9950; PRBMDO
Grant/Contract Number:
AC52-06NA25396; FG02-05ER46248; LANLF100
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 95; Journal Issue: 2; Journal ID: ISSN 2469-9950
American Physical Society (APS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; High Magnetic Field Science
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1341279