Design and Preparation of a Novel Magnet Exhibiting Two Compensation Temperatures Based on Molecular Field Theory

We show the design and preparation of a novel type of magnet exhibiting two compensation temperatures; i.e., the spontaneous magnetization changes its sign twice with changing temperature. The key to obtaining this unusual behavior is the simultaneous incorporation of one antiferromagnetic and two different ferromagnetic interactions through the use of four different spin sources, as predicted by a calculation based on molecular field theory. As a prototype exemplifying this idea, we have prepared a Prussian blue analog, $\left({\mathrm{Ni}}_{0.22}^{\mathrm{II}}{\mathrm{Mn}}_{0.60}^{\mathrm{II}}{\mathrm{Fe}}_{0.18}^{\mathrm{II}}{)}_{1.5}\right[{\mathrm{Cr}}^{\mathrm{III}}\left(\mathrm{CN}{)}_6\right]̇7.6{\mathrm{H}}_2\mathrm{O}$, which exhibits magnetization reversals at 35 and 53 K.