Spin texture in doped Mott insulators with spin-orbit coupling

Abstract

A hole injected into a Mott insulator will gain an internal structure as recently identified by exact numerics, which is characterized by a nontrivial quantum number whose nature is of central importance in understanding the Mott physics. In this work, we show that a spin texture associated with such an internal degree of freedom can explicitly manifest after the spin degeneracy is lifted by a weak Rashba spin-orbit coupling (SOC). It is described by an emergent angular momentum J z = ± 3 2 as shown by both exact diagonalization and variational Monte Carlo calculations, which are in good agreement with each other at a finite size. In particular, as the internal structure such a spin texture is generally present in the hole composite even at high excited energies, such that a corresponding texture in momentum space, extending deep inside the Brillouin zone, can be directly probed by the spin-polarized angle-resolved photoemission spectroscopy (ARPES). This is in contrast to a Landau quasiparticle under the SOC, in which the spin texture induced by SOC will not be protected once the excited energy is larger than the weak SOC coupling strength, away from the Fermi energy. We point out that the spin texture due to the SOC should be monotonically enhanced with reducing spin-spin correlation length in the superconducting-pseudogap phase at finite doping. A brief discussion of a recent experiment of the spinpolarized ARPES will be made.

Exploring spin-polarization in Bi-based high-Tc cuprates

“…So far, present and existing spin-resolved ARPES results have found no signature of a band splitting other than the bilayer splitting. It is thus apparent that further theoretical work is needed to go beyond the conventional framework of Rashba-type spin–orbit interactions 6 – 8 , which cannot explain the current results where no Rashba-like band-splitting is observed.…”

“…Conversely, recent spin- and angle-resolved photoemission spectroscopy (ARPES) measurements on high- cuprates have shown significant spin polarization, implying the presence of spin–momentum locking induced by the spin–orbit interaction 5 . This has prompted theoretical investigations into the role and consequences of the Rashba-type spin–orbit interaction in cuprate superconductors, highlighting the potential importance of this interaction in high- cuprates 6 – 8 . However, the driving force behind the reported spin-polarized electronic states remains unclear, perhaps due to their unique spin texture, which involves a sign reversal of spin polarization from the node to off-nodes, even within one Fermi surface.…”

Mottness, phase string, and high-T c superconductivity

“…( 20) with finite-size ED and DMRG results outlined in Subsection 2.3, as calculated by the VMC method, including the nontrivial angular momentum L z = ±1 in 2D [49] and the momentum structure in the two-leg ladder case, [48] clearly demonstrates that the doped hole in the Mottness gets substantially renormalized by the phase-string effect, whose behavior is fundamentally distinct from the celebrated Landau's quasiparticle as a new quasiparticle of the doped Mott insulator. Recently a single-hole-doped case under a perturbation of a weak spin-orbit coupling (SOC) has been also examined, [50] which 087104-6 has further shown that the twisted hole with the novel angular momentum in Eq. ( 21) is critical to properly describe the response to the SOC as indicated by an excellent agreement between the VMC and ED.…”