Delocalized fermions in underdoped cuprate superconductors

被引:66
|
作者
Sutherland, M
Li, SY
Hawthorn, DG
Hill, RW
Ronning, F
Tanatar, MA
Paglione, J
Zhang, H
Taillefer, L
DeBenedictis, J
Liang, R
Bonn, DA
Hardy, WN
机构
[1] Univ Toronto, Dept Phys, Toronto, ON, Canada
[2] Univ Sherbrooke, Dept Phys, Sherbrooke, PQ J1K 2R1, Canada
[3] Univ Sherbrooke, Regroupement Quebecois Mat Pointe, Sherbrooke, PQ J1K 2R1, Canada
[4] Univ British Columbia, Dept Phys & Astron, Vancouver, BC V5Z 1M9, Canada
[5] Canadian Inst Adv Res, Toronto, ON, Canada
关键词
D O I
10.1103/PhysRevLett.94.147004
中图分类号
O4 [物理学];
学科分类号
0702 ;
摘要
Low-temperature heat transport was used to investigate the ground state of high-purity single crystals of the lightly doped cuprate YBa2Cu3O6.33. Samples were measured with doping concentrations on either side of the superconducting phase boundary. We report the observation of delocalized fermionic excitations at zero energy in the nonsuperconducting state, which shows that the ground state of underdoped cuprates is a thermal metal. Its low-energy spectrum appears to be similar to that of the d-wave superconductor, i.e., nodal. The insulating ground state observed in underdoped La2-xSrxCuO4 is attributed to the competing spin-density-wave order.
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页数:4
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