Mossbauer spectroscopy under a magnetic field to explore the low-temperature spin structure of the layered ferrimagnetic material - {N(n-C4H9)(4)[(FeFeIII)-Fe-II(C2O4)(3)]}(infinity)

摘要

Fe-57 Mossbauer spectroscopy of the metal-assembled layered ferrimagnetic material {N(n-C4H9)(4)[(FeFeIII)-Fe-II(C2O4)(3)]}(infinity) was performed under a high external magnetic field at 4.2 K. This study successfully detected different types of Fe-II and Fe-III high spin sites in the lattices. The hyperfine field values estimated for all the Fe-III high spin sites are close to the expected values, whereas those for Fe-II high spin sites are substantially different to those expected usually. A large fraction of magnetically disordered Fe-III high spin sites were found. It is understood that the layered structure of the compound may have two kinds of sub-lattices-(Fe-A(II)-ox-Fe-A(III)-(...)) and (Fe-B(II)-ox-Fe-B(III)-(...))-along with randomly placed magnetically disordered Fe-C(III) sites, where the, Fe-A(III) and Fe-B(III) are antiferromagnetically aligned. The existence of the magnetically and/or structurally non-equivalent spin sites in the same lattice has been held responsible for the coexistence of different ferrimagnetic interactions leading to the spin glass state, as observed through earlier magnetic and calorimetric measurements. [References: 26]