摘要
Combining in-depth neutron diffraction and systematic bulk studies,we discover that the√5×√5 Fe vacancy order,with its associated block antiferromagnetic order,is the ground state with varying occupancy ratios of the iron 16i and vacancy 4d sites across the phase-diagram of K_(x)Fe_(2)-ySe_(2).The orthorhombic order,with one of the four Fe sites vacant,appears only at intermediate temperatures as a competing phase.The material experiences an insulator to metal crossover when the√5×√5 order is highly developed.Superconductivity occurs in such a metallic phase.
作者
BAO Wei
LI Guan-Nan
HUANG Qing-Zhen
CHEN Gen-Fu
HE Jun-Bao
WANG Du-Ming
MAGreen
QIU Yi-Ming
LUO Jian-Lin
WU Mei-Mei
鲍威;李冠男;黄清镇;陈根富;何俊宝;王笃明;MAGreen;邱义铭;雒建林;武梅梅(Department of Physics,Renmin University of China,Beijing 100872;NIST Center for Neutron Research,National Institute of Standards and Technology,Gaithersburg,MD 20899,USA;Institute of Physics,Chinese Academy of Sciences,Beijing 100190;Department of Materials Science and Engineering,University of Maryland,College Park,MD 20742,USA;Neutron Scattering Laboratory,China Institute of Atomic Energy,Beijing 102413)
基金
Supported by the National Basic Research Program of China under Grant Nos 2012CB921700,2011CBA00112,2011CBA00103 and 2009CB929104
National Natural Science Foundation of China under Grant Nos 11034012,11190024,10974175 and 10934005.
