# Non-conservation of Density of States in Bi$\_2$Sr$\_2$CaCu$\_2$O$\_y$: Coexistence of Pseudogap and Superconducting gap

Source: [Non-conservation of Density of States in Bi$\_2$Sr$\_2$CaCu$\_2$O$\_y$: Coexistence of Pseudogap and Superconducting gap](<https://www.sota2.com/research/paper/68fa25a62c2a3760193b26f6>)

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Data updated: 2025-10-24T10:52:21.977Z

Authors: Anjan K. Gupta, K. -W. Ng

Published: 2002-02-25T17:05:02.000Z

## Abstract

The tunneling spectra obtained within the ab-plane of Bi$\_2$Sr$\_2$CaCu$\_2$O$\_y$ (Bi2212) for temperatures below and above the critical temperature (T$\_c$) are analyzed. We find that the tunneling conductance spectra for the underdoped compound in the superconducting state do not follow the conservation of states rule. There is a consistent loss of states for the underdoped BI2212 implying an underlying depression in the density of states (DOS) and hence the pseudogap near the Fermi energy (E$\_F$). Such an underlying depression can also explain the peak-dip-hump structure observed in the spectra. Furthermore, the conservation of states is recovered and the dip-hump structure disappears after normalizing the low temperature spectra with that of the normal state. We argue that this is a direct evidence for the coexistence of a pseudogap with the superconducting gap.

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/cond-mat/0202450>)

[PDF](<https://arxiv.org/pdf/cond-mat/0202450.pdf>)