Pressure response of the bimetallic chain compound MnNi(NO2)4(en)2; en = ethylenediamine

The compound MnNi(NO2)4(en)2, en = ethylendiamine, is a rare example of a ferromagnetically coupled bimetallic chain (J∥ chain ∼ 2–3 K). Further, for this material, a finite inter-chain coupling triggers an antiferromagnetic (AFM) transition below TN = 2.3 K. Here, we present a susceptibility study of MnNi(NO2)4(en)2 under pressure. From our data, we derive the pressure response of the antiferromagnetic transition temperature TN. Even up to highest pressure of 8.2 kbar we find a very modest increase of TN by only ∼0.1 K. Independently, from a pressure study of the lattice parameters of MnNi(NO2)4(en)2, we calculate the bulk module of the material to ∼8.8 GPa. Combining the data TN(p) with the bulk module yields an anomalously low Grüneisen parameter Γmag of only 0.5(5). We discuss possible scenarios accounting for such a low Grüneisen parameter.

Graphical abstractThis paper presents the pressure-induced enhancement of the transition temperature in the bimetallic chain compound MnNi(NO2)4(en)2.Figure optionsDownload full-size imageDownload as PowerPoint slide