Hole Properties On and Off Magnetization Plateaus in 2D Antiferromagnets

The phenomenon of magnetization plateaus in antiferromagnets under a magnetic field has always been an important topic in magnetism. We propose to probe the elusive physics of plateaus in 2D by considering a hole-doped antiferromagnet and studying the signatures of magnetization plateaus in terms of the properties of holes, coupled to an effective gauge field generated by the spin sector. The latter mediates interaction between the holes, found to be algebraically decaying and long ranged with both Coulombic and dipolar forms outside the plateau and short ranged (local) inside the plateau. The resulting hole spectral weight is significantly broadened off plateau, while it remains sharply peaked on plateau. We also extend the result obtained for a 1D system where finite hole doping gives rise to a shift in the magnetization value of the plateaus.

Figure 1

(a) Feynman diagram of a 2-fermion scattering process mediated by the gauge field. (b) The local interaction vertex counterpart.

Figure 2

One-loop self-energy diagram in the in-plateau case with its local fermion-fermion interaction.

Figure 3

One-loop self-energy diagrams in the out-of-plateau case where the fermion interaction is long ranged. (a) The tadpole diagram. (b) The bubble diagram.

Figure 4

Spectral function $A(\omega )$ at a fixed $|\mathbf{k}|$ for quadratic dispersion around Fermi point (a) in the in-plateau case and (b) in the out-of-plateau case [24].

Figure 5

Spectral function $A(\omega )$ at a fixed $|\mathbf{k}|$ for linearized dispersion at finite doping (a) in the in-plateau case and (b) in the out-of-plateau case [24].