and NMR investigation of charge order in ( K)
- McMaster Univ., Hamilton, ON (Canada); Canadian Institute for Advanced Research, Toronto, ON (Canada)
- Stanford National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
Here, we report 139La and 63Cu NMR investigation of the successive charge order, spin order, and superconducting transitions in superoxygenated La2CuO4+y single crystal with stage-4 excess oxygen order at Tstage≃290 K. We show that the stage-4 order induces tilting of CuO6 octahedra below Tstage, which in turn causes 139La NMR line broadening. The structural distortion continues to develop far below Tstage, and completes at Tcharge≃60 K, where charge order sets in. This sequence is reminiscent of the the charge-order transition in Nd codoped La1.88Sr0.12CuO4 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 Tcharge 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 CuO2 planes. This indicates that charge order in La2CuO4+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 Tspin(≃Tc) =42 K. These findings, including the spatially inhomogeneous nature of the charge-ordered state, are qualitatively similar to the case of La1.885Sr0.115CuO4, but both charge and spin order take place more sharply in the present case.
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- DMR 96-23858; DMR 98-08941; AC02-76SF00515
- OSTI ID:
- 1436968
- Alternate ID(s):
- OSTI ID: 1426012
- Journal Information:
- Physical Review B, Vol. 97, Issue 10; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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