By using solid-state reactions, we successfully synthesize new oxyselenides CsV2Se2−xO (x = 0, 0.5). These compounds containing V2O planar layers with a square lattice crystallize in the CeCr2Si2C structure with the space group of P4/mmm. Another new compound V2Se2O which crystallizes in space group I4/mmm is fabricated by topochemical deintercalation of cesium from CsV2Se2O powder with iodine in tetrahydrofuran(THF). Resistivity measurements show a semiconducting behavior for CsV2Se2O, while a metallic behavior for CsV2Se1.5O, and an insulating feature for V2Se2O. A charge- or spin-density wave-like anomaly has been observed at 168 K for CsV2Se2O and 150 K for CsV2Se1.5O, respectively. And these anomalies are also confirmed by the magnetic susceptibility measurements. The resistivity in V2Se2O exhibits an anomalous log(1/T) temperature dependence, which is similar to the case in parent phase or very underdoped cuprates indicating the involvement of strong correlation. Magnetic susceptibility measurements show that the magnetic moment per V-site in V2Se2O is much larger than that of CsV2Se2−xO, which again suggests the correlation induced localization effect in the former.
@article{arxiv.1803.00703,
title = {Structures and Physical Properties of CsV$_2$Se$_{2-x}$O and V$_2$Se$_2$O},
author = {Hai Lin and Jin Si and Xiyu Zhu and Kehan Cai and Hao Li and Lu Kong and Xiaodong Yu and Hai-Hu Wen},
journal= {arXiv preprint arXiv:1803.00703},
year = {2018}
}