Structure and physical properties of the new layered oxypnictides Sr₄Sc₂O₆M₂As₂ (M = Fe and Co)

Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China - Hefei, Anhui 230026, China

Corresponding author: chenxh@ustc.edu.cn

Received: 9 April 2009
Accepted: 25 May 2009

Abstract

We have successfully prepared the new layered oxypnictides Sr₄Sc₂O₆M₂As₂ (M = Fe and Co). They adopt the tetragonal structure, being the same as that of Sr₄Sc₂O₆Fe₂P₂. The lattice constants are a = 0.4045 nm and c = 1.5802 nm for M = Fe and a = 0.4045 nm and c = 1.5695 nm for M = Co, respectively. Their transport and magnetic properties have been systematically studied. The temperature dependence of the Hall coefficient and the thermoelectric power for the Sr₄Sc₂O₆M₂As₂ compound show a complicated behavior, similar to that of the iron-based parent compounds LnOFeAs and BaFe₂As₂. This suggests that Sr₄Sc₂O₆Fe₂As₂ could be considered as a new parent compound of iron-based superconductors.