Direct evidence of non-Zhang-Rice Cu3+ centers in La2Li0.5Cu0.5O4
DSpace at IIT Bombay
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Title |
Direct evidence of non-Zhang-Rice Cu3+ centers in La2Li0.5Cu0.5O4
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Creator |
MOSKVIN, AS
GIPPIUS, AA TKACHEV, AV MAHAJAN, AV CHAKRABARTY, T PRESNIAKOV, IA SOBOLEV, AV DEMAZEAU, G |
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Subject |
MAGNETIC EXCITATIONS
LA2CU0.5LI0.5O4 COPPER STATE SUPERCONDUCTORS LA2CU1-XLIXO4 SINGLET OXIDES PHASES |
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Description |
A well-isolated Zhang-Rice (ZR) singlet as a ground state of the Cu3+ center in hole-doped cuprates is a leading paradigm in modern theories of high-temperature superconductivity. However, a dramatic temperature evolution of the Li-6,Li-7 NMR signal in La2Li0.5Cu0.5O4, a system with a regular lattice of well-isolated Cu3+ centers, reveals significant magnetic fluctuations and suggests a quasidegeneracy to be a generic property of their ground state at variance with the simple ZR model. We argue for a competition of the ZR state with nearby states formed by a "doped" hole occupying purely oxygen nonbonding a(2g)(pi) and e(u)(pi) orbitals rather than a conventional b(1g)(d(x2-y2))Cu 3d-O 2p hybrid. The temperature variation of the Li-6,Li-7 NMR line shape and spin-lattice relaxation rate point to a gradual slowing down of some magnetic order parameter's fluctuations without distinct signatures of a phase transition down to T = 2 K. This behavior agrees with a stripelike ferrodistortive fluctuating Ammm order in a two-dimensional structure of the (CuLi)O-2 planes accompanied by unconventional oxygen orbital antiferromagnetic fluctuations. DOI: 10.1103/PhysRevB.86.241107
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Publisher |
AMER PHYSICAL SOC
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Date |
2014-10-15T15:21:55Z
2014-10-15T15:21:55Z 2012 |
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Type |
Article
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Identifier |
PHYSICAL REVIEW B, 86(24)
http://dx.doi.org/10.1103/PhysRevB.86.241107 http://dspace.library.iitb.ac.in/jspui/handle/100/15140 |
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Language |
en
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