Tan, GuotaiSong, YuZhang, ChenglinLin, LifangXu, ZhuangHou, TingtingTian, WeiCao, HuiboLi, ShiliangFeng, ShipingDai, Pengcheng2016-09-302016-09-302016Tan, Guotai, Song, Yu, Zhang, Chenglin, et al.. "Electron doping evolution of structural and antiferromagnetic phase transitions in NaFe1−xCoxAs iron pnictides." <i>Physical Review B,</i> 94, no. 1 (2016) American Physical Society: http://dx.doi.org/10.1103/PhysRevB.94.014509.https://hdl.handle.net/1911/91637We use transport and neutron diffraction to study the electronic phase diagram of NaFe1−xCoxAs. In the undoped state, NaFeAs exhibits a tetragonal-to-orthorhombic structural transition below Tsfollowed by a collinear antiferromagnetic (AF) order below TN. Upon codoping to form NaFe1−xCoxAs,Ts and TN are gradually suppressed, leading to optimal superconductivity near Co-doping x=0.025. While transport experiments on these materials reveal an anomalous behavior suggesting the presence of a quantum critical point (QCP) near optimal superconductivity, our neutron diffraction results indicate that commensurate AF order becomes transversely incommensurate with TN>Tc before vanishing abruptly at optimal superconductivity. These results are remarkably similar to electron-doping and isovalent-doping evolution of the AF order in BaFe2−xNixAs2 and BaFe2(As1−xPx)2, thus suggesting a universal behavior in the suppression of the magnetic order in iron pnictides as superconductivity is induced.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttp://dx.doi.org/10.1103/PhysRevB.94.014509