Photo-Enhanced Ferromagnetism in High K+-Containing K-Ni-Cr Prussian Blue Analogues Coated on Rb-Co-Fe Nanocubes

摘要

Many fascinating magnetic behaviors have been identified in Prussian blue analogues (PBAs) with a general chemical formula of AnxnM[M'(CN)n6n]nyn·nHn2nO (denoted as A-M-M’), where M and M’ can be divalent or trivalent transition metal ions and A is a monovalent alkali ion that is accommodated in the voids enclosed by the MNn6nand M'C6 octahedra. Their magnetic characteristics depend not only on the intrinsic nature of the complexes, but can also be greatly altered by extrinsic stimulations, such as the applied pressure or light irradiation. [1]–[3] In particular, one very promising characteristics is the photo-induced magnetism found in A-Co-Fe (with A = K, Na, Rb, Cs), which has been demonstrated to be sensitive to the type and the amount of A+ ion that has been incorporated into the compound. [1]–[3] This behavior is believed to originate from the electron transfer that occurs between the MN6 and M'C6 octahedra, known as the charge transfer induced spin transition (CTIST).[4] In addition, the photo-magnetic responses in nano-sized core/shell heterostructures have recently been found to be sensitive to the shell thickness. [5]–[7] No photo-induced magnetism has been identified in isolated K-Ni-Cr, but noticeable reductions (∼8%) of the magnetization by light irradiation appear when this material is coated on a Rb-Co-Fe nano-cube.[5]