The itinerant state of carriers in pnictide NaCu₂P₂: Role of distortion in CuP₄ tetrahedra

Research & Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences - P.O. Box 603, Beijing 100190, China

^a chenx29@aphy.iphy.ac.cn

Received: 3 September 2010
Accepted: 10 November 2010

Abstract

A new copper-based pnictide NaCu₂P₂, which is isostructural to the superconductor LiCu₂P₂, has been synthesized. The structural analysis reveals that the CuP₄ tetrahedra of this compound are much flattened exhibiting a bigger P-Cu-P angle and a shorter thickness of the P-Cu₂-P layer compared with its counterparts in LiCu₂P₂. It shows metal-like conducting behavior over a temperature range from room temperature down to 2 K. Magnetic measurement indicates it is diamagnetic over the same temperature range. The structural distortion in CuP₄ tetrahedra is thought to be responsible for the metallic character and the absence of superconductivity above 1.65 K. The results demonstrate the distortion in the tetrahedra plays an important role in determining the carrier state in pnictides.