The Fermi Arc and Fermi Pocket in Cuprates in a Short-Range Diagonal Stripe Phase
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O R I G I N A L PA P E R
The Fermi Arc and Fermi Pocket in Cuprates in a Short-Range Diagonal Stripe Phase W. LiMing · Sha Ke · Jiayun Luo · Chengping Yin · Liangbin Hu
Received: 24 September 2012 / Accepted: 30 November 2012 / Published online: 20 December 2012 © Springer Science+Business Media New York 2012
Abstract In this paper, we studied the Fermi arc and the Fermi pocket in cuprates in a short-range diagonal stripe phase with wave vectors (7π/8, 7π/8), which reproduce with a high accuracy the positions and sizes of the Fermi arc and Fermi pocket and the superstructure in cuprates observed by Meng et al. 2009. The low-energy spectral function indicates that the Fermi pocket results from the main band and the shadow band at the Fermi energy. Above the Fermi energy, the shadow band gradually departs away from the main band, leaving a Fermi arc. Thus, we conclude that the Fermi arc and Fermi pocket can be fully attributed to the stripe phase but has nothing to do with pairing. Incorporating a d-wave pairing potential in the stripe phase the spectral weight in the antinodal region is removed, leaving a clean Fermi pocket in the nodal region. Keywords Pseudogap · Stripe phase · Fermi arc
1 Introduction The pseudogap (PG) state of cuprate superconductors in the normal state is still a mystery to the mechanism of high Tc superconductivity. It opens at temperature T ∗ , which is much higher than the transition temperature Tc of superconductivity. The Fermi surface of an underdoped cuprate in the PG phase is suppressed in the antinodal region (around (±π, 0) and (0, ±π)) and shows a residue part (Fermi arc) W. LiMing () · S. Ke · J. Luo · C. Yin · L. Hu Dept. of Physics, and Laboratory of Quantum Information Technology, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China e-mail: [email protected]
around the nodal point (±π/2, ±π/2) [1, 2]. In the overdoping region, however, this phenomenon disappears and a full Fermi surface recovers. The Fermi arc is usually enclosed by a weak pocket (Fermi pocket). This phenomenon has been strongly confirmed by a series of measurements of the angleresolved photo-emission spectroscopy (ARPES) [3–5] and some other techniques. Since the PG is similar to a d-wave gap which opens at the antinodal region and shrinks to zero at the nodal point, it was thought ever as the same gap as the d-wave superconducting gap. This is the one-gap scenario of the PG state, where electrons (or holes) are prepaired incoherently above Tc. More and more evidences, however, showed that the PG is different from the superconducting gap, but a new gap results from such as spin modulation, charge modulation, or spin fluctuation, etc. [6, 7]. For instance, a few years ago, Wen et al. found two different energy scales in the PG state [7], and recently Takeshi et al. found electrons and holes cannot be prepaired at such temperatures much higher than Tc [8]. Meng et al. observed rich structures of the PG state in superconductor Bi2 Sr2−x Lax CuO6+δ by ARP
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