We use neutron scattering to study vanadium (hole)-doped LiFe1−xVxAs. In the undoped state, LiFeAs exhibits superconductivity at Tc=18 K and transverse incommensurate spin excitations similar to electron overdoped iron pnictides. Upon vanadium-doping to form LiFe0.955V0.045, the transverse incommensurate spin excitations in LiFeAs transform into longitudinally elongated in a similar fashion as that of potassium (hole) doped Ba0.7K0.3Fe2As2, 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 Seff with a spin crossover ground state arising from the inter-orbital scattering of itinerant electrons.
@article{arxiv.1912.11860,
title = {Strong local moment antiferromagnetic spin fluctuations in V-doped LiFeAs},
author = {Zhuang Xu and Guangyang Dai and Yu Li and Zhiping Yin and Yan Rong and Long Tian and Panpan Liu and Hui Wang and Lingyi Xing and Yuan Wei and Ryoichi Kajimoto and Kazuhiko Ikeuchi and D. L. Abernathy and Xiancheng Wang and Changqing Jin and Xingye Lu and Guotai Tan and Pengcheng Dai},
journal= {arXiv preprint arXiv:1912.11860},
year = {2019}
}