Origin of superconducting carriers in “non-doped” T′-(La,RE)2CuO4 (RE = Sm, Eu, Gd, Tb, Lu, and Y) prepared by molecular beam epitaxy
✍ Scribed by M. Noda; A. Tsukada; H. Yamamoto; M. Naito
- Publisher
- Elsevier Science
- Year
- 2005
- Tongue
- English
- Weight
- 139 KB
- Volume
- 426-431
- Category
- Article
- ISSN
- 0921-4534
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✦ Synopsis
We have performed a systematic investigation of the variations of the lattice constants with substituent rare-earth element concentration x in the nominally undoped superconductors T 0 -La 3þ 2Àx RE 3þ
x CuO 4 (RE = Sm, Eu, Gd, Tb, Lu, and Y), which we have recently discovered using MBE. The results show both the in-plane and out-of-plane lattice constants (a 0 and c 0 linearly decrease with x, whose extrapolation to x = 2 agrees well with the reported a 0 and c 0 values for each T 0 -RE 2 CuO 4 . This behavior is what one would expect simply from the ionic size difference between La 3+ and RE 3+ . The absence of the Cu-O bond stretching due to electron-doping, which is commonly observed in electron-doped T 0 and infinite-layer superconductors, implies that electron-doping via oxygen deficiencies is, at least, not a main source of charge carriers.