Superconductivity, the Jahn-Teller phenomenon, and Mott’s insulating state are just three of the broader range of phases present in the phase diagram of alkali metal fullerides A$_3$C$_{60}$ (A=Na, K, Rb, Cs). The primary goal of this master’s thesis is to investigate doped fullerenes where we deviate from half-occupancy of the conduction band. In this master’s work, we examined compounds Yb$_2$AC$_{60}$ (A=K, Rb, Cs) using nuclear magnetic resonance (NMR) as the method. Understanding the structure of molecular orbitals $t_{1u}$, forming the electronic band, suggests metallic properties of the compounds. With nuclear magnetic resonance, we measured $^{13}$C NMR spectra in the temperature range from 20 K to 340 K, providing insights into the half-width and relative shift of $^{13}$C NMR frequency. Additionally, we determined spin lattice relaxation times $T_1$ for all three compounds at various temperatures. Temperature-independent shifts of $^{13}$C NMR spectra and the $\frac{1}{T_1T}$ parameter indicate a metallic state with a low density of states at the Fermi energy for the studied compounds. Moreover, an increase in $\frac{1}{T_1T}$ values above approximately 200 K suggests an additional mechanism contributing to spin-lattice relaxation, attributed to intrinsic C$_{60}^{5-}$ dynamics. The reinforcement of spin-lattice relaxation is describable within the Bloembergen-Purcell-Pound (BPP) model, from which we extracted frequencies $\tau_0$ and activation energies $E_a$ to describe intrinsic dynamics. The values of $E_a$ range from 62 meV to 106 meV and are comparable to the values for Jahn-Teller dynamics in some other alkali metal fullerides.
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