Magnetic Properties of a Canted Antiferromagnet Mn(N$_{3}$)$_{ 2}$(4,4'-bpy)

Results of magnetic susceptibility \textit{$\chi $}($T)$, isothermal magnetization $M(H)$, and heat capacity $C(T)$ measurements on a manganese complex with mixed ligands Mn(N$_{3})_{2}$(4,4'-bpy) (4,4'-bpy = 4,4'-bipyridine) are reported. The crystal structure of this three-dimensional manganese azide network is tetragonal, with lattice parameters $a=b$ = 8.1 {\AA} and $c$ = 16.7 {\AA}. Fitting the high $T$ data of \textit{$\chi $}($T)$ on powder samples resulted an effective moment \textit{$\mu $}$_{eff}$ = 4.9 \textit{$\mu $}$_{B}$ for the Mn$^{2+}$ moments, and a strong antiferromagnetic interaction of \textit{$\theta $} = - 120 K. An antiferromagnetic transition with rather high transition temperature of 39 K was observed in the $M(T)$/$H$ data of Mn(N$_{3})_{2}$(4,4'-bpy), and large non-compensated component in \textit{$\chi $}($T)$ below T$_{N}$ was seen. The result of $M(H)$ measures showed that Mn(N$_{3})_{2}$(4,4'-bpy) behaves like a ferrimagnet below T$_{N}$, with a small coercive field of $H_{coe}$ = 150 G at 1.8 K. A sizable anomaly was observed in $C(T)$ data, and this confirms the long-range magnetic phase transition and the T$_{N}$. The magnetic behavior of this compound is discussed in terms of a strong Mn-Mn coupling through this unique network with end-to-end azido bridges, and compared with the magnetic behavior of its iron isostructural analogue Fe(N$_{3})_{2}$(4,4'-bpy).