NMR Study on Metal-Insulator Transition and High T_c Superconductivity

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In this project, unusual electronic properties of the strongly correlated systems such as quaternary compound YNi_2B_2C and RPt_2B_2C have been investigated by NMR measurements. The enhancements of T_1T and Knight shift of ^<11>B at low temperature show an importance of the effects of 3d spin fluctuations in the superconducting YNi_2B_2C families.We have also prepared some Cu Spinel compounds (i.e. CuIr_2S_4 etc.)with enriched isotope of ^<33>S,spin ladder(VO)_2P_2O_7, NdBa_2Cu_3O_7and BaPb_<1-x>Bi_xO_3 with ^<137>Ba. With using of these isotopes, we have successfully observed NMR signals at the atomic sites, which have been investigated at the first time. Magnetic and local electronic states at the Metal-Insulator transition have been discussed.