Caging-Pnictogen-Induced Superconductivity in Skutterudites IrX3 (X = As, P)

Abstract

Here we report on a new kind of compound, XδIr4X12-δ (X = P, As), the first hole-doped skutterudites superconductor. We provide atomic resolution images of the caging As atoms using scanning transmission electron microscopy (STEM). By inserting As atoms into the caged structure under a high pressure, superconductivity emerges with a maximum transition temperature (Tc) of 4.4 K (4.8 K) in IrAs3 (IrP3). In contrast to all of the electron-doped skutterudites, the electronic states around the Fermi level in XδIr4X12-δ are dominated by the caged X atom, which can be described by a simple body-centered tight-binding model, implying a distinct paring mechanism. Our density functional theory (DFT) calculations reveal an intimate relationship between the pressure-dependent local-phonon mode and the enhancement of Tc. The discovery of XδIr4X12-δ provides an arena to investigate the uncharted territory of hole-doped skutterudites, and the method proposed here represents a new strategy of carrier doping in caged structures, without introducing extra elements.

14 pages, 4 figures, 1 table

References in corpus (4)

• Superconductivity to 262 kelvin via catalyzed hydrogenation of yttrium at high pressures
• Superconductivity in the New Platinum Germanides MPt4Ge12 (M = Rare-earth and Alkaline-earth Metals) with Filled Skutterudite Structure
• Superconductivity in novel Ge-based skutterudites: {Sr,Ba}Pt_4Ge_{12}
• Superconductivity in alkaline earth metal-filled skutterudites BaxIr4X12 (X = As, P)

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