Eur. Phys. J. B 69, 473-482 (2009)
https://doi.org/10.1140/epjb/e2009-00200-x

Systematic effective field theory investigation of spiral phases in hole-doped antiferromagnets on the honeycomb lattice

¹ Center for Research and Education in Fundamental Physics, Institute for Theoretical Physics, Bern University, Sidlerstrasse 5, 3012 Bern, Switzerland
² Condensed Matter Theory Group, Department of Physics, Massachusetts Institute of Technology (MIT), 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
³ Facultad de Ciencias, Universidad de Colima, Bernal Díaz del Castillo 340, Colima, 28045, Mexico
⁴ Institute for Theoretical Physics, ETH Zürich, Schafmattstrasse 32, 8093 Zürich, Switzerland

Corresponding author: ^a fjjiang@itp.unibe.ch

Received: 8 December 2008
Revised: 27 April 2009
Published online: 13 June 2009

Abstract

Motivated by possible applications to the antiferromagnetic precursor of the high-temperature superconductor Na_xCoO₂.yH₂O, we use a systematic low-energy effective field theory for magnons and holes to study different phases of doped antiferromagnets on the honeycomb lattice. The effective action contains a leading single-derivative term, similar to the Shraiman-Siggia term in the square lattice case, which gives rise to spirals in the staggered magnetization. Depending on the values of the low-energy parameters, either a homogeneous phase with four or a spiral phase with two filled hole pockets is energetically favored. Unlike in the square lattice case, at leading order the effective action has an accidental continuous spatial rotation symmetry. Consequently, the spiral may point in any direction and is not necessarily aligned with a lattice direction.