Effect of Pressure on Magnetic Properties of Hexacyanochromates

Z. Mitróvá, S. Maťaš, M. Mihalik, M. Zentková Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 040 01 Košice, Slovak Republic Z. Arnold and J. Kamarád Institute of Physics of the AS CR, v.v.i., Na Slovance 2, 182 21 Prague 8, Czech Republic

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Received: 9 07 2007;

We present the study of pressure effect on magnetic properties of TM2+3 [CrIII(CN)6 ]2 · nH2 O ferrimagnets and ferromagnets (TM = Cr and Co) under pressures up to 0.9 GPa. Applied pressure strengthens super-exchange interaction in Cr2+-prussian blue analogues with dominant antiferromagnetic interaction JAF leading to increase in the Curie temperature TC (ΔTc /Δp=29.0 K/GPa) and reduces TC of Co2+-prussian blue analogues with dominant ferromagnetic interaction JF (ΔTc /Δp=-1.8 K/GPa). The rise of JAF interaction is attributed to the enhanced value of the single electron overlapping integral S. On the other hand, the applied pressure slightly affects bonding angles between magnetic ions mediated by the cyano-bridge and reduces the strength of magnetic coupling. Changes of the magnetization curve with pressure can be attributed to changes of magnetic anisotropy. The reduction of magnetization with pressure observed on Cr2+-prussian blue analogues can be explained by pressure induced transition from Cr2+ high spin state to Cr2+ low spin state. All pressure induced changes are reversible.

DOI: 10.12693/APhysPolA.113.469 PACS numbers: 75.30.Cr, 75.50.Ee, 75.50.Gg, 75.50.Xx