Quasiparticle vanishing driven by geometrical frustration

Abstract

We investigate the single hole dynamics in the triangular t − J model. We study the structure of the hole spectral function, assuming the existence of a 120• magnetic Néel order. Within the self-consistent Born approximation (SCBA) there is a strong momentum and t sign dependence of the spectra, related to the underlying magnetic structure and the particle-hole asymmetry of the model. For positive t, and in the strong coupling regime, we find that the low energy quasiparticle excitations vanish outside the neighbourhood of the magnetic Goldstone modes; while for negative t the quasiparticle excitations are always well defined. In the latter, we also find resonances of magnetic origin whose energies scale as (J/t) 2/3 and can be identified with string excitations. We argue that this complex structure of the spectra is due to the subtle interplay between magnonassisted and free hopping mechanisms. Our predictions are supported by an excellent agreement between the SCBA and the exact results on finite size clusters. We conclude that the conventional quasiparticle picture can be broken by the effect of geometrical magnetic frustration.

Single-hole properties of thet−Jmodel on the honeycomb lattice

“…For the t-J z model, one can also form a direct expansion in powers of t/J z . This series has been computed to order (t/J z ) 28 21 . These series are available from the authors upon request.…”

Novel Bi-Polaronic Ground State in K/Si(111):B

“…presenting a triangular pattern such as SiC(0001) [10,11], C/Si(111) [12] and more recently Sn/Ge(111) at low temperature [13]. Moreover, it has been proposed that non-negligible exchange coupling between neighboring dangling bonds electron could lead to the formation of a half-filled frustrated antiferromagnetic triangular network at surface [7,10,15,16] ducting surfaces [17]. Angle-resolved photoemission spectroscopy (ARPES) is known to be a powerful tool since it provides great insights in the nature of the single particle excitation spectra, especially in correlated systems.…”

10.1007/s11451-008-2009-9

“…(1) on the spin-up sublattice and by the equation (12) on the spin-down sublattice. We omit the prime and distinguish the spin-up and spin-down sublattices by the index.…”