Chemical potential shift in lightly doped to overdopedBi2Sr2Ca

Abstract

We have studied the chemical potential shift in the high-temperature superconductor Bi 2 Sr 2 Ca 1Ϫx R x Cu 2 O 8ϩy (RϭPr, Er͒, where the hole concentration is varied from 0.025 to 0.17 per Cu, by precise measurements of core-level photoemission spectra. The result shows that the shift is depressed in the underdoped region as in the case of La 2Ϫx Sr x CuO 4 ͑LSCO͒ but the depression is much weaker than in LSCO. The observed shift in the present system can be relatively well explained by numerical results on the doped two-dimensional Hubbard model and suggests that the change of the electronic structure induced by hole doping is less influenced by stripe fluctuations than in LSCO.

Angle-resolved photoemission studies of the cuprate superconductors

“…Therefore, we cannot answer the questions of whether the two-component electronic structure observed in LSCO for 5-7% doping is also present in the Bi2212 case, or how the metallic state emerges in the latter system. Core level spectroscopy results, however, suggest a behavior intermediate between the one seen on LSCO and the simple linear shift of the chemical potential (Harima et al, 2002).…”

Topological Criticality on Brink of the Mott Transition in High-TcSuperconductors

“…Such behavior indicates that this point could be a QCP while the associated critical fluctuations might be responsible for the unconventional normal state behavior [2]. Experiments appear to exclude any broken symmetry around this point although a sharp change in transport properties is observed [3] and ∂µ/∂x becomes vanishingly small due to slow chemical potential shift implying a divergence of charge susceptibility [17]. We argue that due to topological excitations indeed such a singularity arises at µ c in the local charge susceptibility χ c = ∂n e /∂µ, where n e ≡ c α (rτ )c α (rτ ) is the electron filling.…”

Pseudogap in Doped Mott Insulators is the Near-Neighbor Analogue of the Mott Gap

“…Experimentally, whether ∆µ vanishes or not appears to be cuprate dependent. For example, in La 2−x Sr x CuO 4 [15] (LSCO), the chemical potential remains pinned roughly at 0.4eV above the top of the LHB, while for Nd 2−x Ce x CuO 4 (NDCO) [16] and Bi 2 Sr 2 Ca 1−x R x Cu 2 O 8+y (BSCO) [17,18,19,20], the chemical potential jumps upon doping and scales roughly as δ 2 as obtained here. Because stripes require ∆µ = 0, they have been invoked [21] to explain the origin of the mid-gap states in LSCO.…”