TY - JOUR
T1 - Pressure-induced magnetic switching and linkage isomerism in K 0.4Fe4[Cr(CN)6]2.8·16H 2O
T2 - X-ray absorption and magnetic circular dichroism studies
AU - Coronado, Eugenio
AU - Giménez-López, M. Carmen
AU - Korzeniak, Tomasz
AU - Levchenko, Georgiy
AU - Romero, Francisco M.
AU - Segura, Alfredo
AU - García-Baonza, Valentín
AU - Cezar, Julio C.
AU - De Groot, Frank M.F.
AU - Milner, Alla
AU - Paz-Pasternak, Moshe
PY - 2008/11/19
Y1 - 2008/11/19
N2 - The effect of applied pressure on the magnetic properties of the Prussian blue analogue K0.4Fe4[Cr(CN)6] 2.8·16H2O (1) has been analyzed by dc and ac magnetic susceptibility measurements. Under ambient conditions, 1 orders ferromagnetically at a critical temperature (Tc) of 18.5 K. Under application of pressure in the 0-1200 MPa range, the magnetization of the material decreases and its critical temperature shifts to lower temperatures, reaching Tc = 7.5 K at 1200 MPa. Pressure-dependent Raman and Mössbauer spectroscopy measurements show that this striking behavior is due to the isomerization of some CrIII-C≡N-FeII linkages to the CrIII-N≡C-FeII form. As a result, the ligand field around the iron(II) centers increases, and the diamagnetic low-spin state is populated. As the number of diamagnetic centers in the cubic lattice increases, the net magnetization and critical temperature of the material decrease considerably. The phenomenon is reversible: releasing the pressure restores the magnetic properties of the original material. However, we have found that under more severe pressure conditions, a metastable sample containing 22% CrIII-N≡C-FeII linkages can be obtained. X-ray absorption spectroscopy and magnetic circular dichroism of this metastable sample confirm the linkage isomerization process.
AB - The effect of applied pressure on the magnetic properties of the Prussian blue analogue K0.4Fe4[Cr(CN)6] 2.8·16H2O (1) has been analyzed by dc and ac magnetic susceptibility measurements. Under ambient conditions, 1 orders ferromagnetically at a critical temperature (Tc) of 18.5 K. Under application of pressure in the 0-1200 MPa range, the magnetization of the material decreases and its critical temperature shifts to lower temperatures, reaching Tc = 7.5 K at 1200 MPa. Pressure-dependent Raman and Mössbauer spectroscopy measurements show that this striking behavior is due to the isomerization of some CrIII-C≡N-FeII linkages to the CrIII-N≡C-FeII form. As a result, the ligand field around the iron(II) centers increases, and the diamagnetic low-spin state is populated. As the number of diamagnetic centers in the cubic lattice increases, the net magnetization and critical temperature of the material decrease considerably. The phenomenon is reversible: releasing the pressure restores the magnetic properties of the original material. However, we have found that under more severe pressure conditions, a metastable sample containing 22% CrIII-N≡C-FeII linkages can be obtained. X-ray absorption spectroscopy and magnetic circular dichroism of this metastable sample confirm the linkage isomerization process.
UR - http://www.scopus.com/inward/record.url?scp=56449089594&partnerID=8YFLogxK
U2 - 10.1021/ja8047046
DO - 10.1021/ja8047046
M3 - מאמר
AN - SCOPUS:56449089594
VL - 130
SP - 15519
EP - 15532
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 46
ER -