Laser-excited ultrahigh-resolution photoemission spectroscopy of Na xCoO 2·yH 2O: Evidence for pseudogap formation

T. Shimojima; T. Yokoya; T. Kiss; A. Chainani; S. Shin; T. Togashi; S. Watanabe; C. Zhang; C. T. Chen; K. Takada; T. Sasaki; H. Sakurai; E. Takayama-Muromachi

doi:10.1103/PhysRevB.71.020505

Laser-excited ultrahigh-resolution photoemission spectroscopy of Na _xCoO ₂·yH ₂O: Evidence for pseudogap formation

T. Shimojima, T. Yokoya, T. Kiss, A. Chainani, S. Shin, T. Togashi, S. Watanabe, C. Zhang, C. T. Chen, K. Takada, T. Sasaki, H. Sakurai, E. Takayama-Muromachi

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29 Citations (Scopus)

Abstract

We have studied the temperature (T)-dependent electronic structure near the Fermi level of the layered cobaltate superconductor, Na _0.35CoO ₂·1.3H ₂O, and related materials, using laser-excited ultrahigh-resolution photoemission spectroscopy. We observe the formation of a pseudogap (PG) with an energy scale of ∼20 meV in Na _0.35CoO ₂·1.3H ₂O and Na _0.35CoO ₂·0.7H ₂O, which is clearly absent in Na _0.7CoO ₂. The energy scale of the PG is larger than the expected value for the superconducting gap, suggesting an additional competing order parameter at low T. We discuss implications of the PG in relation to available transport and magnetic susceptibility results.

Original language	English
Article number	020505
Journal	Physical Review B - Condensed Matter and Materials Physics
Volume	71
Issue number	2
DOIs	https://doi.org/10.1103/PhysRevB.71.020505
Publication status	Published - Jan 2005
Externally published	Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics

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10.1103/PhysRevB.71.020505

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Shimojima, T., Yokoya, T., Kiss, T., Chainani, A., Shin, S., Togashi, T., Watanabe, S., Zhang, C., Chen, C. T., Takada, K., Sasaki, T., Sakurai, H., & Takayama-Muromachi, E. (2005). Laser-excited ultrahigh-resolution photoemission spectroscopy of Na _xCoO ₂·yH ₂O: Evidence for pseudogap formation. Physical Review B - Condensed Matter and Materials Physics, 71(2), [020505]. https://doi.org/10.1103/PhysRevB.71.020505

Shimojima, T, Yokoya, T, Kiss, T, Chainani, A, Shin, S, Togashi, T, Watanabe, S, Zhang, C, Chen, CT, Takada, K, Sasaki, T, Sakurai, H & Takayama-Muromachi, E 2005, 'Laser-excited ultrahigh-resolution photoemission spectroscopy of Na _xCoO ₂·yH ₂O: Evidence for pseudogap formation', Physical Review B - Condensed Matter and Materials Physics, vol. 71, no. 2, 020505. https://doi.org/10.1103/PhysRevB.71.020505

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title = "Laser-excited ultrahigh-resolution photoemission spectroscopy of Na xCoO 2·yH 2O: Evidence for pseudogap formation",

abstract = "We have studied the temperature (T)-dependent electronic structure near the Fermi level of the layered cobaltate superconductor, Na 0.35CoO 2·1.3H 2O, and related materials, using laser-excited ultrahigh-resolution photoemission spectroscopy. We observe the formation of a pseudogap (PG) with an energy scale of ∼20 meV in Na 0.35CoO 2·1.3H 2O and Na 0.35CoO 2·0.7H 2O, which is clearly absent in Na 0.7CoO 2. The energy scale of the PG is larger than the expected value for the superconducting gap, suggesting an additional competing order parameter at low T. We discuss implications of the PG in relation to available transport and magnetic susceptibility results.",

author = "T. Shimojima and T. Yokoya and T. Kiss and A. Chainani and S. Shin and T. Togashi and S. Watanabe and C. Zhang and Chen, {C. T.} and K. Takada and T. Sasaki and H. Sakurai and E. Takayama-Muromachi",

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doi = "10.1103/PhysRevB.71.020505",

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T2 - Evidence for pseudogap formation

AU - Shimojima, T.

AU - Yokoya, T.

AU - Kiss, T.

AU - Chainani, A.

AU - Shin, S.

AU - Togashi, T.

AU - Watanabe, S.

AU - Zhang, C.

AU - Chen, C. T.

AU - Takada, K.

AU - Sasaki, T.

AU - Sakurai, H.

AU - Takayama-Muromachi, E.

PY - 2005/1

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N2 - We have studied the temperature (T)-dependent electronic structure near the Fermi level of the layered cobaltate superconductor, Na 0.35CoO 2·1.3H 2O, and related materials, using laser-excited ultrahigh-resolution photoemission spectroscopy. We observe the formation of a pseudogap (PG) with an energy scale of ∼20 meV in Na 0.35CoO 2·1.3H 2O and Na 0.35CoO 2·0.7H 2O, which is clearly absent in Na 0.7CoO 2. The energy scale of the PG is larger than the expected value for the superconducting gap, suggesting an additional competing order parameter at low T. We discuss implications of the PG in relation to available transport and magnetic susceptibility results.

AB - We have studied the temperature (T)-dependent electronic structure near the Fermi level of the layered cobaltate superconductor, Na 0.35CoO 2·1.3H 2O, and related materials, using laser-excited ultrahigh-resolution photoemission spectroscopy. We observe the formation of a pseudogap (PG) with an energy scale of ∼20 meV in Na 0.35CoO 2·1.3H 2O and Na 0.35CoO 2·0.7H 2O, which is clearly absent in Na 0.7CoO 2. The energy scale of the PG is larger than the expected value for the superconducting gap, suggesting an additional competing order parameter at low T. We discuss implications of the PG in relation to available transport and magnetic susceptibility results.

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Laser-excited ultrahigh-resolution photoemission spectroscopy of Na _xCoO ₂·yH ₂O: Evidence for pseudogap formation

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