$\sim$475    $-36\pm 2$        $15\pm 8$         $12\pm 2$         $16\pm 5$         $9\pm 5$

  : \[tab:5/tc\] Comparison of effective magnetic exchange couplings for parent compounds of copper-based and iron-based superconductors obtained by fitting spin waves with a Heisenberg Hamiltonian with NN ($J_{1a}, J_{1b}$), NNN ($J_{2a},J_{2b}$), and NNNN ($J_3$). The N$\rm \acute{e}$el temperatures for different materials are also listed.

The effects of hole and electron doping on the magnetic correlations and excitations
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As discussed before [@johnston; @stewart; @paglione10], superconductivity in Fe-based materials can be induced via electron/hole doping, pressure, and isoelectronic substitution. Figures 2a and 2b show the electronic phase diagrams of hole and electron doping on BaFe$_2$As$_2$, respectively. In the undoped state, BaFe$_2$As$_2$ exhibits simultaneous structural and magnetic phase transitions below $\sim$138 K, changing from the high-temperature paramagnetic tetragonal phase to the low-temperature orthorhombic phase with the collinear AF structure (Fig. 1b) [@qhuang]. Upon electron-doping BaFe$_2$As$_2$ by partially replacing Fe by Co or Ni to form BaFe$_{2-x}T_x$As$_2$, the static AF order is suppressed and superconductivity emerges [@johnston; @stewart; @paglione10]. From systematic transport and magnetic measurements of single crystals [@nni08; @jhchu09], the phase diagram for BaFe$_{2-x}$Co$_x$As$_2$ was established, where the single structural/magnetic phase transition in BaFe$_2$As$_2$ splits with increasing Co-doping. Neutron diffraction experiments 