Magnetism in Na-filled Fe-based skutterudites

Abstract

The interplay of superconductivity and magnetism is a subject of ongoing interest, stimulated most recently by the discovery of Fe-based superconductivity and the recognition that spin-fluctuations near a magnetic quantum critical point may provide an explanation for the superconductivity and the order parameter. Here we investigate magnetism in the Na filled Fe-based skutterudites using first principles calculations. NaFe4Sb12 is a known ferromagnet near a quantum critical point. We find a ferromagnetic metallic state for this compound driven by a Stoner type instability, consistent with prior work. In accord with prior work, the magnetization is overestimated, as expected for a material near an itinerant ferromagnetic quantum critical point. NaFe4P12 also shows a ferromagnetic instability at the density functional level, but this instability is much weaker than that of NaFe4Sb12, possibly placing it on the paramagnetic side of the quantum critical point. NaFe4As12 shows intermediate behavior. We also present results for skutterudite FeSb3, which is a metastable phase that has been reported in thin film form.

Thermoelectric properties of the unfilled skutteruditeFeSb3from first principles and Seebeck local probes

“…They find a ferromagnetic ground state and also study phonons and filler atoms. These results have been confirmed by Xing et al 6 , finding a ferromagnetic ground state with LSDA and PBE functionals. These results will serve as a basis for comparison with our theoretical study of bulk FeSb 3 and the study of the thermoelectric properties.…”

Effects of partial La filling and Sb vacancy defects on CoSb3 skutterudites

“…While the high mobility is thermoelectrically favorable, the high lattice thermal conductivity is not. To improve the performance of CoSb 3 toward state-of-the-art mid-temperature thermoelectric materials, extensive experimental and theoretical investigations have focused on filling the naturally formed nanosized cages with alkali metals, alkaline earth metals, or rare earth filler atoms [17,18,19,20,21], or doping at the Co and/or Sb sites [22,23], or implementing both measures simultaneously [24,25,26,27,28,29]. In the context of phonon-glass electron-crystal paradigm [3,30], the filler atoms rattle in the cage and strongly scatter the heat-carrying phonons towards a phonon-glass behavior [31], while the dopants optimize the electronic band structure towards an electron-crystal behavior [32].…”

Add a Pinch of Tetrel: The Transformation of a Centrosymmetric Metal into a Nonsymmorphic and Chiral Semiconductor

“…Centrosymmetric skutterudites MPn 3 , crystallizing in the cubic space group Im3 ̄, have been extensively studied for their use as thermoelectric materials. [26][27][28][29][30][31][32][33] A partial or full replacement of pnictogen atoms with Ge in the skutterudite structures has been reported. [34][35][36][37] Many skutterudites can be electronically tuned by means of aliovalent substitution.…”