| Description |
Single Molecule Magnets (SMMs): During early 1990’s, a new class of magnetic materials has emerged, called SMMs which possess large spin ground state (S) and negative/Ising anisotropy associated with the total spin-ground state. It has been shown by various research groups that SMMs and spincoupled metallic rings have potential applications in; (i) high-density information storage (ii) quantum computing (iii) low-temperature magnetic refrigerants, etc. To explore these applications for day today life, the factors which control the SMMs properties need to be understood clearly. To do so, we have systematically synthesized family of tetra-nuclear transition metal clusters [Co(II)4, Mn(III)2Mn(II)2 and Cu(II)4] using phosphonates and carboxylates as ligands with varying electronic spin-ground states. The magnetic and electronic properties of these tetra-nuclear clusters will be discussed. In addition, the modeling of the nicely resolved hyperfine structures from the trimer-monomer center of Cu4 cluster will be discussed, under strong and weak exchange limits of spin-coupled centers. In part II, the synthesis, structural and magnetic characterization of hexanuclear, [Fe(III)6(OH)2(O)2{(C4N2H2SMe)CO2H}2(Me3CCO2)1 0], Iron(III) complex will be discussed. DC magnetic susceptibility and high-frequency high field EPR measurements performed on the polycrystalline sample showed that hexanuclear, Fe(III)6 has a well isolated S = 5 ground state and negative/Ising type magnetic anisotropy with significant rhombic character. However this molecule did not show any SMMs properties because of the fast relaxation due to efficient quantum tunneling of magnetization (QTM) at zero magnetic field. The history behind this spectacular study will be discussed in details. |