Increase in the Magnetic Ordering Temperature (Tc) as a Function of the Applied Pressure for A2Mn[Mn(CN)6] (A = K, Rb, Cs) Prussian Blue Analogues

M Sugimoto; S Yamashita; H Akutsu; Y Nakazawa; J G DaSilva; C M Kareis; Joel S Miller

doi:10.1021/acs.inorgchem.7b01402

Increase in the Magnetic Ordering Temperature (T_c) as a Function of the Applied Pressure for A₂Mn[Mn(CN)₆] (A = K, Rb, Cs) Prussian Blue Analogues

Inorg Chem. 2017 Sep 5;56(17):10452-10457. doi: 10.1021/acs.inorgchem.7b01402. Epub 2017 Aug 15.

Authors

M Sugimoto¹, S Yamashita¹, H Akutsu¹, Y Nakazawa¹, J G DaSilva², C M Kareis^{2

3}, Joel S Miller^{2

3}

Affiliations

¹ Department of Chemistry, Graduate School of Science, Osaka University , Machikaneyama 1-1, Toyonaka, Osaka 560-0043, Japan.
² Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States.
³ Material Research Science and Engineering Center, University of Utah , Salt Lake City, Utah 84112, United States.

PMID: 28809550
DOI: 10.1021/acs.inorgchem.7b01402

Abstract

Magnetization measurements under pressure reveal that the external hydrostatic pressure significantly increases in the ferrimagnetic transition temperature, T_c, for A₂Mn[Mn(CN)₆] (A = K, Rb, Cs). In the case of monoclinic A = K and Rb, dT_c/dp values are 21.2 and 14.6 K GPa^-1, respectively, and T_c increases by 53 and 39%, respectively, from ambient pressure to 1.0 GPa. The cubic A = Cs compound also shows a monotonous increase with an initial rate of 4.22 K GPa^-1 and about 11.4 K GPa^-1 above 0.6 GPa, and an overall T_c increase by 26% at 1.0 GPa. The increase in T_c is attributed to deformation of the structure such that the Mn^II-N≡C angle decreases with increasing pressure. The smaller the alkali cation, the greater the decrease in the Mn^II-N≡C angle induced by pressure and the larger the increase of dT_c/dp. This is in accordance with the ambient-pressure structures for A₂Mn[Mn(CN)₆] (A = K, Rb, Cs), which have decreasing Mn^II-N≡C angles that correlate to the observed increasing T_cs as K > Rb > Cs. The large increase in T_c for the A = K compound is the highest class among several cyano-bridged metal complexes. The tuning of the transition temperature by such a weak pressure may lead to additional applications such as switching devices.