Imaging Doped Holes in a Cuprate Superconductor with High-Resolution Compton Scattering

Abstract

The high-temperature superconducting cuprate La(2-x)Sr(x)CuO(4) (LSCO) shows several phases ranging from antiferromagnetic insulator to metal with increasing hole doping. To understand how the nature of the hole state evolves with doping, we have carried out high-resolution Compton scattering measurements at room temperature together with first-principles electronic structure computations on a series of LSCO single crystals in which the hole doping level varies from the underdoped (UD) to the overdoped (OD) regime. Holes in the UD system are found to primarily populate the O 2p(x)/p(y) orbitals. In contrast, the character of holes in the OD system is very different in that these holes mostly enter Cu d orbitals. High-resolution Compton scattering provides a bulk-sensitive method for imaging the orbital character of dopants in complex materials.

Doping evolution of Zhang-Rice singlet spectral weight: A comprehensive examination by x-ray absorption spectroscopy

“…The evolution of the orbital character of the doped holes with p has been recently demonstrated by Compton scattering. 22 Therefore, the experimental reason for the kink at p ≈ 0.02 and the slope change of S(p) for the entire doping regime could be that the O 2p states lose part of its spectral weight to Cu 3d states due to the stronger Cu 3d character of doped holes with increasing p. Comparing the linear fit of the S L data (black dot line) with the solid line in Fig. 3(b), S L (p) has a weaker slope change than S(p) does.…”

Non-scalar contribution of potential in crystals

“…This scenario may be supported by the Compton scattering measurements, which reveal that the carrier of underdoped La 2−x Sr x CuO 4 is concentrated around O(1). [12] To confirm this scenario, another parent material of hole-doped high-T c , HgBa 2 CuO 4 , is considered. This material can reach higher T c,M ax (∼ 95 K) after best doping of holes.…”

Probing the Fermi surface by positron annihilation and Compton scattering

“…Sampling all electrons equally, Compton scattering does not suffer from this drawback, and has recently been used to probe the orbital character of holes doped into La 2x Sr x CuO 4 . 113 In a combined experimental and theoretical tour de force, Sakurai et al were able to show that on the underdoped side of the phase diagram, the holes were primarily in the O 2p x /p y orbitals, but on the overdoped side they mostly dope into the Cu d orbitals. Robust from surface effects, defects or impurities, Compton scattering was shown to be a powerful probe of the orbital character of dopants in electronically complex materials.…”