Pressure-induced enhancement of the magnetic anisotropy in Mn(N(CN)2)2

Using dc and ac magnetometry, the pressure dependence of the magnetization of the three-dimensional antiferromagnetic coordination polymer Mn(N(CN)2)2 was studied up to 12 kbar and down to 8 K. The antiferromagnetic transition temperature, TN, increases dramatically with applied pressure (P), where a change from TN(P=ambient)=16.0K to TN(P=12.1kbar)=23.5K was observed. In addition, a marked difference in the magnetic behavior is observed above and below 7.1 kbar. Specifically, for P<7.1 kbar, the differences between the field-cooled and zero-field-cooled magnetizations, the coercive field, and the remanent magnetization decrease with increasing pressure. However, for P>7.1 kbar, the behavior is inverted. Additionally, for P>8.6 kbar, minor hysteresis loops are observed. All of these effects are evidence of the increase of the superexchange interaction and the appearance of an enhanced exchange anisotropy with applied pressure.