State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China.
Phys Rev Lett. 2012 Aug 3;109(5):057003. doi: 10.1103/PhysRevLett.109.057003. Epub 2012 Jul 31.
We elucidate the existing controversies in the newly discovered K-doped iron selenide (K(x)Fe(2-y)Se(2-z)) superconductors. The stoichiometric KFe(2)Se(2) with √2 × √2 charge ordering was identified as the parent compound of K(x)Fe(2-y)Se(2-z) superconductor using scanning tunneling microscopy and spectroscopy. The superconductivity is induced in KFe(2)Se(2) by either Se vacancies or interacting with the antiferromagnetic K(2)Fe(4)Se(5) compound. In total, four phases were found to exist in K(x)Fe(2-y)Se(2-z): parent compound KFe(2)Se(2), superconducting KFe(2)Se(2) with √2 × √5 charge ordering, superconducting KFe(2)Se(2-z) with Se vacancies, and insulating K(2)Fe(4)Se(5) with √5 × √5 Fe vacancy order. The phase separation takes place at the mesoscopic scale under standard molecular beam epitaxy conditions.
我们阐明了新发现的 K 掺杂铁硒化物（K(x)Fe(2-y)Se(2-z)）超导体中存在的争议。利用扫描隧道显微镜和光谱学，确定具有 √2 × √2 电荷有序的化学计量 KFe(2)Se(2)是 K(x)Fe(2-y)Se(2-z)超导体的母体化合物。超导性是通过硒空位或与反铁磁 K(2)Fe(4)Se(5)化合物相互作用在 KFe(2)Se(2)中诱导产生的。总共发现 K(x)Fe(2-y)Se(2-z)中有四种相存在：母体化合物 KFe(2)Se(2)、具有 √2 × √5 电荷有序的超导 KFe(2)Se(2)、具有硒空位的超导 KFe(2)Se(2-z)和具有 √5 × √5 Fe 空位有序的绝缘 K(2)Fe(4)Se(5)。在标准分子束外延条件下，相分离发生在介观尺度上。
