skip to main content


This content will become publicly available on March 14, 2019

Title: La 139 and Cu 63 NMR investigation of charge order in La 2 CuO 4 + y ( T c = 42 K)

Here, we report 139La and 63Cu NMR investigation of the successive charge order, spin order, and superconducting transitions in superoxygenated La 2CuO 4+y single crystal with stage-4 excess oxygen order at T stage≃290 K. We show that the stage-4 order induces tilting of CuO 6 octahedra below T stage, which in turn causes 139La NMR line broadening. The structural distortion continues to develop far below Tstage, and completes at T charge≃60 K, where charge order sets in. This sequence is reminiscent of the the charge-order transition in Nd codoped La 1.88Sr 0.12CuO 4 that sets in once the low-temperature tetragonal phase is established. We also show that the paramagnetic 63Cu NMR signals are progressively wiped out below T charge due to enhanced low-frequency spin fluctuations in charge-ordered domains, but the residual 63Cu NMR signals continue to exhibit the characteristics expected for optimally doped superconducting CuO 2 planes. This indicates that charge order in La 2CuO 4+y does not take place uniformly in space. In addition, unlike the typical second-order magnetic phase transitions, low-frequency Cu spin fluctuations as probed by 139La nuclear spin-lattice relaxation rate do not exhibit critical divergence at T spin(≃T c) =42 K. These findings, including the spatiallymore » inhomogeneous nature of the charge-ordered state, are qualitatively similar to the case of La 1.885Sr 0.115CuO 4, but both charge and spin order take place more sharply in the present case.« less
 [1] ;  [2]
  1. McMaster Univ., Hamilton, ON (Canada); Canadian Institute for Advanced Research, Toronto, ON (Canada)
  2. Stanford National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
Publication Date:
Grant/Contract Number:
DMR 96-23858; DMR 98-08941; AC02-76SF00515
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 97; Journal Issue: 10; Journal ID: ISSN 2469-9950
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
OSTI Identifier: