Composition-dependent bulk properties in intercalated transition metal dichalcogenides Co1/3(1±δ)NbS2

초록

We report a systematic study of the composition-dependent bulk properties in Co1/3(1 +/-delta)NbS2 single crystals across a series of precisely controlled cobalt compositions with -4% delta 8%. By tuning the cobalt stoichiometry, we find that the topological Hall effect is critically sensitive to the intercalant cobalt composition and is completely suppressed when the cobalt composition exceeds delta = +4%. We observe that the longitudinal conductivity is also strongly influenced by the cobalt composition, reaching its maximum value just before the disappearance of the topological Hall effect. Furthermore, heat capacity measurements reveal distinct Sommerfeld coefficients (gamma ) across different compositions, which exhibit a clear linear scaling with the inverse of the ordinary Hall coefficient (R-1 H ). These results demonstrate that composition tuning in Co1/3(1 +/-delta)NbS2 systematically modifies the low-energy electronic degree of freedom, moving beyond a simple dilute impurity picture. Finally, we use the microscopic spin Hamiltonian to explain the stability of the experimentally observed M-point modulation vector and the corresponding triple-Q magnetic order. Our findings highlight that the topological properties of this system are highly tunable through precise control of the intercalant concentration, offering a new perspective on the competition between electronic and magnetic orders in intercalated transition-metal dichalcogenides.

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