The effects of chemical doping and hydrostatic pressure on {Tc} of Y{sub 1{minus}y}Ca{sub y}Ba{sub 2}Cu{sub 3}O{sub x} and NdBa{sub 2}Cu{sub 3}O{sub x} single crystals
The authors studied {Tc} of YBa{sub 2}Cu{sub 3}O{sub x} (Y123), Y{sub 0.89}Ca{sub 0.11}Ba{sub 2}Cu{sub 3}O{sub x} (YCa123) and NdBa{sub 2}Cu{sub 3}O{sub x} (Nd123) single crystals with various oxygen contents x. Compared to {Tc}(a) of Y123 the {Tc}(x) curves of YCa123 are shifted to lower oxygen contents and the maximum transition temperature T{sub c,max} decreases with increasing Ca content whereas in Nd123 {Tc}(x) is shifted to higher oxygen contents and T{sub c,max} is increased. According to the universal parabolic {Tc}(n{sub h}) behavior the differences in {Tc}(x) of Y123, YCa123 and Nd123 can be ascribed to different hole concentrations n{sub h} in the CuO{sub 2} planes caused by doping via changes in chemistry or structure. In order to study the influence of structural changes on {Tc} they examined the hydrostatic pressure effect d{Tc}/dp (p {le} 0.6GPa). In the underdoped region, at n{sub h} {approx} 0.11, the examined compounds show a peak in d{Tc}/dp which is very pronounced for systems with well ordered CuO chains. As this peak occurs at the same n{sub h} in all investigated systems it is not caused by oxygen ordering, but its origins might be found in a strong influence of lattice deformations on the electronic structure.
- Research Organization:
- Univ. Karlsruhe (DE)
- OSTI ID:
- 20012899
- Journal Information:
- Journal of Low Temperature Physics, Journal Name: Journal of Low Temperature Physics Journal Issue: 3-4 Vol. 117; ISSN JLTPAC; ISSN 0022-2291
- Country of Publication:
- United States
- Language:
- English
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