Effects of Pressure on the Magnetic Properties of Prussian Blue Analogue Heterostuctures

Magnetic studies on the Prussian blue analogues (PBAs), Li$_x$Cu[Fe(CN)$_6$]$_y\cdot$$m$H$_2$O (CuFe-PBA) and Li$_k$Ni[Cr(CN)$_6$]$_l \cdot$$n$H$_2$O (NiCr-PBA), as well as CuFe@NiCr-PBA core-shell heterostructures, have been conducted under pressures ranging from ambient to $\approx$ 1.4~GPa and at temperatures of 2 - 90~K. Our results for the single phase CuFe-PBA indicate robust magnetic properties under the range of pressures studied: a \textit{T$_c$} of 20 K was observed at all pressures.\footnote{M. Verdaguer, G. S. Girolami, Magnetism: Molecules to Materials V, (Wiley 2005) p 303; M. Okubo \textit{et al.}, Angew. Chem. Int. Ed. \textbf{50} (2011) 6269.} However, our pressure studies of single phase NiCr-PBA are consistent with the results of Zentkov\'a \textit{et al.} up to 1~GPa.\footnote{ M. Zentkov\'a \textit{et al.}, J. Phys.: Condens. Matter \textbf{19} (2007) 266217.} At pressures above 1.0 GPa, the decrease in magnetization is accompanied by a decrease in the \textit{T$_c$}, an indication of changes in the superexchange value, an effect not reported by Zentkov\'a \textit{et al.} Lastly, our results on the effects of pressure on the magnetic properties of heterostructed PBAs, specifically CuFe@NiCr-PBA, will be presented.