Redox mechanism for the generation of holes in TlBa{sub 1{minus}{ital x}}Sr{sub {ital x}}LaCuO{sub 5+{delta}}: A neutron-diffraction study

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.52.4427· OSTI ID:90501

Sharma, R ^[1]; Sundaresan, A ^[2]; Sequeira, A ^[1]; Gupta, L C ^[2]; Sharon, M ^[3]

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1. Solid State Physics Division, Bhabha Atomic Research Centre, Bombay 400085 (India)
2. Solid State Physics Group, Tata Institute of Fundamental Research, Bombay 400005 (India)
3. Department of Chemistry, Indian Institute of Technology, Bombay 400076 (India)

Our neutron-diffraction study of the single Tl-O layered TlBa{sub 1{minus}{ital x}}Sr{sub {ital x}}LaCuO{sub 5+{delta}} system ({ital x}=0.0, 0.4, 0.7, and 1.0) shows that the in-plane Cu-O(2) bond length decreases monotonically with increase of {ital x}. This is consistent with the introduction of holes in CuO{sub 2} layers or the appearance of superconductivity in the sample with {ital x}=0.4 ({ital T}{sub {ital c}}=22 K) and increase of {ital T}{sub {ital c}} with {ital x}, {ital T}{sub {ital c}}=25 and 30 K for samples with {ital x}=0.7 and 1.0, respectively. Further, the valence of copper, derived from Cu-O bond length, increases with increase of {ital x} despite the fact that the O content decreases as {ital x} increases. This clearly suggests that the internal redox mechanism due to the overlap of the empty Tl 6{ital s} band with the filled Cu 3{ital d}{sub {ital x}}{sup 2}{minus}{ital y}{sup 2} band is responsible for the generation of holes, and therefore superconductivity, in these materials.

• OSTI ID: 90501
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 6 Vol. 52; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BARIUM OXIDES
BOND LENGTHS
COPPER OXIDES
HIGH-TC SUPERCONDUCTORS
HOLES
LANTHANUM OXIDES
NEUTRON DIFFRACTION
REDOX PROCESS
STRONTIUM OXIDES
SUPERCONDUCTIVITY
THALLIUM OXIDES
TRANSITION TEMPERATURE