Erratum: Crystal and magnetic structures of the spin-trimer compounds ${\text{Ca}}_3$${\text{Cu}}_{3-x}$${\text{Ni}}_x$$({\text{PO}}_4{)}_4$ $(x=0,1,2)$ [Phys. Rev. B 76, 174433 (2007)]

Figure 1

The zeroth unit cell of ${\mathrm{Ca}}_3{\mathrm{Cu}}_{3-x}{\mathrm{Ni}}_x{\left({\mathrm{PO}}_4\right)}_4$ ($x=2$) showing the configuration of the Ni and Cu spins. Some of the Ni-spins from the neighboring cells are shown for better visibility of the trimers. The straight dashed lines are drawn through the trimers to show the same antiferromagnetic coupling in all the trimers. The unit cell constants at $T=25$ K are $a=17.724$ Å, $b=4.815$ Å, $c=17.836$ Å, $\beta =123.{756}^{\circ }$ ($C2/c$ space group). The spins in the middle of the cell along the $c$ direction between the dotted lines belong to orbit 2 (Cu2, Ni21, and Ni22 spins) and have propagation vector ${\mathrm{k}}_2=[-\frac{1}{2}\frac{1}{2}0]$, the other spins belong to orbit 1 (Cu1, Ni11, and Ni12 spins) and have propagation vector ${\mathrm{k}}_1=\left[\frac{1}{2}\frac{1}{2}0\right]$.