Magnetic and M?ssbauer Studies in Molecular-based magnets NBu_4M_A~(II)Fe~(III)(OX)_3 (M_A=Co, Fe)

摘要

The mixed valency character and antiferromagnetic coupling in molecule magnets materials NBu_4M_A~(II)[Fe~(III)(OX)3] (M_A=Co, Fe) were investigated by magnetic measurements and M?ssbauer spectroscopy.In the sample NBu_4Co~(II)[Fe~(III)(OX)_3],the appearence of temperature point of spin-glass phase transition and magnetic phase transition under the zero-field-cooled AC magnetic measurements with the temperature range 5-100 K.The sample NBu_4Fe~(II)[Fe~(III)(OX)_3] were carried out in the cooling modes in a field,and the sample exhibits multiple magnetic pole reversals in the warming mode magnetic measurements.The phenomenon of multiple magnetic pole reversals occurs in some of those ferrimagnetic materials consisting of magnetic anisotropy ions and two or more types of antiferromagnetically ordered magnetic ions.The compound NBu4Fe~(II)[Fe~(III)(OX)_3] contains two different spin carries; ie: Fe(II) (S_(Fe(II)) = 2), Fe(III) (S_(Fe(III)) = 5/2) comes from the M?ssbauer studies.