High-resolution x-ray scattering studies of structural phase transitions in underdoped La{sub 2-x}Ba{sub x}CuO{sub 4}

Journal Article · Thu Nov 01 00:00:00 EDT 2007 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.76.184121· OSTI ID:21052764

Zhao, Y; Castellan, J P; Ruff, J P. C.; Dunsiger, S R; Dabkowska, H A ^[1]; Gaulin, B D ^[1]; Gu, G D ^[2]

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1. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada)
2. Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

We have studied structural phase transitions in high quality underdoped La{sub 2-x}Ba{sub x}CuO{sub 4} single crystals using high-resolution x-ray scattering techniques. Critical properties associated with the continuous high temperature tetragonal (HTT) (I4/mmm) to middle temperature orthorhombic (MTO) (Bmab) phase transition were investigated in single crystal samples with x=0.125, 0.095, and 0.08, and we find that all behavior is consistent with three-dimensional XY criticality, as expected from theory. Power law behavior in the orthorhombic strain, 2(a-b)/(a+b), is observed over a remarkably wide temperature range, spanning most of the MTO regime in the phase diagram. Low temperature measurements investigating the low temperature tetragonal (LTT) (P4{sub 2}/ncm) phase, below the strongly discontinuous MTO{yields}LTT phase transition, in x=0.125 and x=0.095 samples show that the LTT phase is characterized by relatively broad Bragg scattering, compared with that observed at related wave vectors in the HTT phase. This shows that the LTT phase is either an admixture of tetragonal and orthorhombic phases or that it is orthorhombic with very small orthorhombic strain, consistent with the ''less orthorhombic'' low temperature structure previously reported in mixed La{sub 2-x}Sr{sub x-y}Ba{sub y}CuO{sub 4} single crystals. We compare the complex temperature-composition phase diagram for the location of structural and superconducting phase transitions in underdoped La{sub 2-x}Ba{sub x}CuO{sub 4} and find good agreement with results obtained on polycrystalline samples.

• OSTI ID: 21052764
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 76, Issue 18; Other Information: DOI: 10.1103/PhysRevB.76.184121; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM COMPOUNDS
COMPARATIVE EVALUATIONS
CUPRATES
HIGH-TC SUPERCONDUCTORS
LANTHANUM COMPOUNDS
MONOCRYSTALS
ORTHORHOMBIC LATTICES
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
POLYCRYSTALS
RESIDUAL STRESSES
RESOLUTION
SOLIDS
STRAINS
TEMPERATURE RANGE
TETRAGONAL LATTICES
THREE-DIMENSIONAL CALCULATIONS
X-RAY DIFFRACTION