High-pressure synthesis of new filled skutterudite compounds SrT ₄As₁₂ (T = Fe, Ru, Os)

Abstract

We have succeeded in synthesizing samples of new filled skutterudite compounds SrT4As12 (T=Fe, Ru, and Os) using a high-pressure synthesis technique. These compounds have lattice constants of 8.351, 8.521, and 8.561 Å, respectively. The physical properties of the compounds are reported for the first time. The temperature dependences of the electrical resistivity for SrT4As12 (T=Fe, Ru, and Os) exhibit metallic behaviors. The electrical resistivity and magnetic measurements indicates that SrOs4As12 is a new superconductor with a transition temperature of 4.8 K. A broad maximum of magnetic susceptibility at around 50 K and a large electronic specific heat coefficient of 58 mJ mol-1 K-2 suggest that SrFe4As12 is a nearly ferromagnetic metal with spin fluctuations of Fe 3d electrons.

Suppression of ferromagnetic spin fluctuations in the filled skutterudite superconductor SrOs4As12 revealed by As75

“…Polycrystalline SrOs 4 As 12 samples were prepared at high temperatures and high pressures using a Kawaitype double-stage multianvil high-pressure apparatus [31]. The lattice constant of SrOs 4 As 12 with a body centered cubic structure (space group: Im3) has been determined by x-ray diffraction measurements to be 8.561 A [31].…”

“…Polycrystalline SrOs 4 As 12 samples were prepared at high temperatures and high pressures using a Kawaitype double-stage multianvil high-pressure apparatus [31]. The lattice constant of SrOs 4 As 12 with a body centered cubic structure (space group: Im3) has been determined by x-ray diffraction measurements to be 8.561 A [31]. Magnetic susceptibility measurement was performed using a magnetic properties measurement system (MPMS, Quantum Design, Inc.) under a magnetic field of 5 T. NMR and NQR measurements of 75 As (I = 3 2 , γN 2π = 7.2919 MHz/T, Q = 0.29 barns) nuclei were conducted using a lab-built phase-coherent spin-echo pulse spectrometer.…”

“…Recently, new filled-skutterudite arsenide compounds SrT 4 As 12 (T = Fe, Ru, Os) have been synthesized using a high-pressure synthesis technique [31], which provides a new opportunity of systematic studies of the role of d electrons with 3d, 4d and 5d. For the 5d electron system, SrOs 4 As 12 was found to be a new superconductor with a transition temperature of T c = 4.8 K [31]. For the 3d and 4d electron systems, on the other hand, SrFe 4 As 12 and SrRu 4 As 12 do not exhibit superconductivity down to 2 K, although the electrical resistivities show metallic behavior [31].…”

“…The inset show the temperature dependence of β. (b) Temperature dependence of electrical resistivity from Ref [31]…”

“…. (c) Temperature dependence of volume magnetic susceptibility in the superconducting state estimated from the zero-field cooled magnetic susceptibility data reported in Ref [31]…”