Sr2Pt8−xAs: a layered incommensurately modulated metal with saturated resistivity

IUCrJ

Alla Arakcheeva¹  Andrea Pisoni¹  László Forró¹  Sergiy Katrych¹  Edoardo Martino¹  Maja D. Bachmann²  Toni Helm²  Kimberly A. Modic²  Philip J. W. Moll²  Oleg V. Yazyev³  Gabriel Autès³ 

[1] Laboratory of Physics of Complex Matter, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland;Max-Planck-Institute for Chemical Physics of Solids, Dresden 01187, Germany;National Centre for Computational Design and Discovery of Novel Materials MARVEL, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland;

关键词: platinum-based metallic compounds;    incommensurately modulated structure;    vacancies;    Mooij correlation;    composite materials;    inorganic materials;    density functional theory;   

DOI  :  10.1107/S2052252518007303

来源: DOAJ

【 摘 要 】

The high-pressure synthesis and incommensurately modulated structure are reported for the new compound Sr2Pt8−xAs, with x = 0.715 (5). The structure consists of Sr2Pt3As layers alternating with Pt-only corrugated grids. Ab initio calculations predict a metallic character with a dominant role of the Pt d electrons. The electrical resistivity (ρ) and Seebeck coefficient confirm the metallic character, but surprisingly, ρ showed a near-flat temperature dependence. This observation fits the description of the Mooij correlation for electrical resistivity in disordered metals, originally developed for statistically distributed point defects. The discussed material has a long-range crystallographic order, but the high concentration of Pt vacancies, incommensurately ordered, strongly influences the electronic conduction properties. This result extends the range of validity of the Mooij correlation to long-range ordered incommensurately modulated vacancies. Motivated by the layered structure, the resistivity anisotropy was measured in a focused-ion-beam micro-fabricated well oriented single crystal. A low resistivity anisotropy indicates that the layers are electrically coupled and conduction channels along different directions are intermixed.

【 授权许可】

Unknown