We use neutron scattering to study Vanadium (hole)-doped LiFe_1−xV_xAs. In the undoped state, LiFeAs exhibits superconductivity at T_c = 18 K and transverse incommensurate spin excitations similar to electron overdoped iron pnictides. Upon Vanadium doping to form LiFe_0.955V_0.045, the transverse incommensurate spin excitations in LiFeAs transform into longitudinally elongated ones in a similar fashion to that of potassium (hole)-doped Ba_0.7K_0.3Fe₂As₂ but with dramatically enhanced magnetic scattering and elimination of superconductivity. This is different from the suppression of the overall magnetic excitations in hole-doped BaFe₂As₂ and the enhancement of superconductivity near optimal hole doping. These results are consistent with density function theory plus dynamic mean field theory calculations, suggesting that Vanadium doping in LiFeAs may induce an enlarged effective magnetic moment S_eff with a spin crossover ground state arising from the inter-orbital scattering of itinerant electrons.

我们使用中子散射来研究钒（空穴）掺杂的LiFe _{1- x} V _x As。在未掺杂状态下，LiFeAs在T _c  = 18 K时表现出超导性，并且与电子过量掺杂的铁素体相似，横向自旋不对称。钒掺杂形成LiFe _0.955 V _0.045时，LiFeAs中的横向不对称自旋激发以类似于掺杂钾（空穴）的Ba _0.7 K _0.3 Fe ₂ As _2的方式转变为纵向伸长的激发。但大大增强了磁散射并消除了超导性。这与抑制掺杂空穴的BaFe ₂ As ₂中的整体磁激励和提高最佳空穴掺杂附近的超导性不同。这些结果与密度函数理论和动态平均场理论的计算结果一致，这表明LiFeAs中的钒掺杂可能会导致有效磁矩S _eff增大，且其巡回电子的轨道间散射引起自旋交叉基态。