arXiv subjects

S. Matsuishi

Publications and source records attributed to S. Matsuishi.

21 records · Page 2Linked to original sources

arXiv2008

Magnetic order in CaFe1-xCoxAsF (x = 0, 0.06, 0.12) superconductor compounds

A Neutron Powder Diffraction (NPD) experiment has been performed to investigate the structural phase transition and magnetic order in CaFe1-xCoxAsF superconductor compounds (x = 0, 0.06, 0.12). The parent compound CaFeAsF undergoes a tetragonal to orthorhombic phase transition at 134(3) K, while the magnetic order in form of a spin-density wave (SDW) sets in at 114(3) K. The antiferromagnetic structure of the parent compound has been determined with a unique propagation vector k = (1,0,1) and the Fe saturation moment of 0.49(5)uB aligned along the long a-axis. With increasing Co doping, the long range antiferromagnetic order has been observed to coexist with superconductivity in the orthorhombic phase of the underdoped CaFe0.94Co0.06AsF with a reduced Fe moment (0.15(5)uB). Magnetic order is completely suppressed in optimally doped CaFe0.88Co0.12AsF. We argue that the coexistence of SDW and superconductivity might be related to mesoscopic phase separation.

cond-mat.supr-con↗

arXiv2008

Pressure-induced superconductivity in Iron pnictide compound SrFe2As2

Electrical resistivity under high pressure have been measured on nominally pure SrFe2As2 up to 14 GPa. The resistivity drop appeared with increasing pressure, and we clearly observed zero resistivity. The maximum of superconducting transition temperature (Tc) is 38 K. The value is corresponding to the one of optimally doping AFe2As2 (A=Sr, Ba) system with K+ ions at the A2+ site.

cond-mat.supr-con↗

arXiv2004

Observation of Jonscher Law in AC Hopping Conduction of Electron-Doped Nanoporous Crystal 12CaO7Al2O3 in THz Frequency Range

We have performed terahertz time-domain spectroscopy of carrier-doped nanoporous crystal 12CaO7Al2O3 showing the Mott variable range hopping at room temperature. The real part of the dielectric constant clearly demonstrates the nature of localized carriers. The frequency dependence of both the real and imaginary parts of the dielectric constant can be simply explained by assuming two contributions: a dielectric response by the parent compound with no carriers and an AC hopping conduction with the Jonscher law generally reported up to GHz range. The possible obedience to the Jonscher law in the THz range suggests a relaxation time of the hopping carriers much faster than 1ps in the carrier-doped 12CaO7Al2O3.

cond-mat.mtrl-sci↗