Thallium NMR study of the chain semiconductor TlTaS3

We report a study of the 203Tl and 205Tl Nuclear Magnetic Resonance of the ternary semiconductor TlTaS3 that shows a chain structure. Our measurements show noticeable intra-chain (Tl–Tl) and inter-chain (Tl–Ta) indirect nuclear spin–spin interactions. These couplings result from the overlap of the Tl and Ta electron wave functions across the intervening S atom, in contrast with the expected 1D-behavior of the compound. The experimental results are in good agreement with the calculated electronic band structure. The role of the 6s2 electron pair of Tl in interatomic interactions is discussed.