Figure 1

(a) Classical spin structure factor $S(\pi ,0)$ (normalized to 1) vs $T$, for the $J_H$’s indicated, using the periodic boundary condition $8\times 8$ cluster and $J_{\mathrm{NN}}=0.015$. The oscillations in the data are indicative of the error bars. (b) Density of states $N(\omega )$ of each orbital ($\mu =\mathrm{\text{chemical}}$ potential), using TBC with $L=512$, at $T=0\mathrm{K}$ and $J_H=0.1\mathrm{eV}$, for the perfect ($\pi$, 0) magnetic state. (c) Resistance $R$ vs $L$ (TBC $8\times 8$) for the FM and AFM directions of the perfect ($\pi$, 0) magnetic state ($J_H=0.1\mathrm{eV}$). (d) The occupation at the FS $n(\mu )$ (see text) of the three orbitals vs $T$, using $L=256$. A coupling $J_{\mathrm{NN}}=0.016$ (0.014) along the $x$ ($y$) axis was used (see text).Reuse & Permissions

Figure 2

$A(\mathbf{k},\omega )$ at $\omega =\mu$ (TBC $8\times 8$ $L=512$). The model used (see Ref. 23) includes the staggered As modulation out of the FeAs layer. Thus, our results are in the folded Brillouin zone convention, and for this reason two electron pockets (as opposed to just one) are centered at $X$ in the panels above. The pocket elongated vertically at $X$ would corresponds to a pocket at $Y$ in the unfolded convention if the As modulation is considered via a quasicrystal momentum [23]. (a)–(c) are for $J_H=0.1\mathrm{eV}$. The red, green, and blue points displayed in the online color version are for the $xz$, $yz$, and $xy$ orbitals, respectively. (a) $T=40\mathrm{K}$, below $T_N$. The ($\pi$, 0) magnetic order induces $yz$-orbital electron satellite pockets. (b) $T=110\mathrm{K}\sim T_N$. In this regime, the MC configurations display small coexisting patches of ($\pi$, 0) and (0, $\pi$) order (see text), creating almost symmetric $xz$ and $yz$ features around $\Gamma$. (c) Large $T=360\mathrm{K}$, with no remnants of the ($\pi$, 0) order. The FS becomes a broader version of the noninteracting FS at $J_H=0$, shown in (d) at $T=100\mathrm{K}$.Reuse & Permissions

Figure 3

Resistance $R$ of the SF model calculated via MC simulations, at $J_H=0.1\mathrm{eV}$ and using the $L=256$ TBC $8\times 8$ cluster. $T_N$ is indicated, and the magnetic susceptibilities ${\chi }_S$ are also shown. The FM-AFM directions asymmetry is evident at low $T$ (note that the FM and AFM labels simply refer to the $y$ and $x$ directions, respectively, and not to fully FM or AFM spin configurations). As $T$ increases the symmetry is restored, and the curves display a peak at $T_N$. A small symmetry-breaking difference $r_{\mathrm{NN}}=1.14$ is used (see text). In green (dashed line) are the results for random spin configurations, showing that their $R$ is smaller than in the MC results near $T_N$. The width of the $\chi$ peaks extend to $\sim 1.5T_N$, in agreement with neutron scattering for ${\mathrm{CaFe}}_2{\mathrm{As}}_2$ [38].Reuse & Permissions

Figure 4

Resistance $R$ calculated using a $L=64$ TBC $16\times 16$ cluster, with $J_{\mathrm{NN}}=0.032$ (0.028) along the $x$ ($y$) axis. The spin configurations are generated via $H_{\mathrm{Heis}}$, while the $R$ measurements use the full $H_{\mathrm{SF}}$, at $J_H=0.1\mathrm{eV}$. The rest of the notation is as in Fig. 3.Reuse & Permissions

Figure 5

(a) Typical MC-generated classical spin configuration on an $8\times 8$ cluster at $T_N\sim 110\mathrm{K}$, $J_H=0.1\mathrm{eV}$, and $J_{\mathrm{NN}}=0.016$ (0.014) along the $x$ ($y$) axis. The solid (dashed) lines denote AFM (FM) NN correlations, of intensity proportional to the width. Solid (dashed) lines are red (blue) in color version. (b) The dominant orbital at the FS at each site for the configuration used in (a), calculated using $n(\mu )$ as in Fig. 1d. Red (green) denote the $xz$ ($yz$) orbital, with a size proportional to the density.Reuse & Permissions