Single-molecule magnets

This thesis discusses the syntheses and magnetization studies of several single-molecule magnets. These single-molecule magnets are also shown to display resonant magnetization tunneling. In chapter 1 an introduction into this area of research and similar areas of research are presented. In chapter 2 several complexes from a family of molecules with {dollar}rmlbrack Mnsb4Osb3Xrbracksp{lcub}6+{rcub}{dollar} cores are shown to behave as single-molecule magnets based on AC magnetic susceptibility measurements on microcrystalline and dilute frozen solution samples. In chapter 3 more detailed magnetic studies are reported for one complex from the Mn4 family of molecules--{dollar}rmlbrack Mnsb4Osb3Cl(Osb2CCHsb3)sb3(dbm)sb3rbrack,{dollar} where dbm is dibenzoylmethane. It is shown that this Mn{dollar}sb4{dollar} complex exhibits resonant magnetization tunneling based on the observation of steps on magnetic hysteresis loops, ac magnetic susceptibility studies and the observation of a temperature-independent rate of magnetization relaxation below 0.6 K. In chapters 4 through 6 the syntheses and magnetization studies of several new Mn{dollar}sb{lcub}12{rcub}{dollar} molecules with general composition {dollar}rmlbrack Mnsb{lcub}12{rcub}Osb{lcub}12{rcub}(Osb2CR)sb{lcub}16{rcub}(Hsb2O)sb4rbrack{dollar} are reported. From ac susceptibility measurements it is shown that some of these complexes exhibit much faster magnetic relaxation than others. Also, steps are observed at constant intervals of field on the magnetization hysteresis loops collected on some of these Mn{dollar}sb{lcub}12{rcub}{dollar} complexes. This is evidence of field-tuned resonant magnetization tunneling.