Thermopower and resistivity of La-doped thallium 1201 and bismuth 2204 superconductors
C K Subramaniam; C V N Rao; A B Kaiser; H J Trodahl; A Mawdsley; N E Flower; J L Tallon; C K Subramaniam; Dept. of Phys., Victoria Univ., Wellington, New Zealand; C V N Rao; Dept. of Phys., Victoria Univ., Wellington, New Zealand; A B Kaiser; Dept. of Phys., Victoria Univ., Wellington, New Zealand; H J Trodahl; Dept. of Phys., Victoria Univ., Wellington, New Zealand; A Mawdsley; Dept. of Phys., Victoria Univ., Wellington, New Zealand; N E Flower; Dept. of Phys., Victoria Univ., Wellington, New Zealand; J L Tallon; Dept. of Phys., Victoria Univ., Wellington, New Zealand
Журнал:
Superconductor Science and Technology
Дата:
1994-01-01
Аннотация:
We have measured the thermopower and resistivity of two series of cuprate superconductor, Tl<sub>0.5</sub>Pb<sub>0.5</sub>Sr<sub>2-x</sub>La<sub>x</sub>CuO<sub>5</sub> and Bi<sub>2</sub>Sr<sub>2-x</sub>La<sub>x</sub>CuO<sub>6+y</sub>, which possess a single CuO<sub>2</sub> plane. In each series, the hole concentration can be varied by changing the La content, permitting investigation of the overdoped, maximum-T<sub>c</sub> and underdoped regimes. The thermopower follows a pattern similar to that seen in superconductor series with more than one CuO<sub>2</sub> plane, namely an approximately linear decrease as temperature increases well above T<sub>c</sub>. However, the thermopower shows a minimum above T<sub>c</sub> followed by a maximum as temperature increases for samples with a small thermopower and high T<sub>c</sub>. The magnitude of thermopower as a function of T<sub>c</sub> is in general agreement with the universal behaviour found for other cuprate superconductors.
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