Phase Relationship of MgSi at High Pressures and High Temperatures and Thermoelectric Properties of MgSi.

Magnesium silicide (MgSi) is a promising eco-friendly thermoelectric material, which has been extensively studied in recent times. However, its phase behavior at high pressures and temperatures remains unclear. To this end, in this study, X-ray diffraction analysis was conducted at high pressures ranging from 0 to 11.

Possible Tomonaga-Luttinger spin liquid state in the spin-1/2 inequilateral diamond-chain compound KCuAlO(SO).

KCuAlO(SO) is a highly one-dimensional spin-1/2 inequilateral diamond-chain antiferromagnet. Spinon continuum and spin-singlet dimer excitations are observed in the inelastic neutron scattering spectra, which is in excellent agreement with a theoretical prediction: a dimer-monomer composite structure, where the dimer is caused by strong antiferromagnetic (AFM) coupling and the monomer forms an almost isolated quantum AFM chain controlling low-energy excitations. Moreover, muon spin rotation/relaxation spectroscopy shows no long-range ordering down to 90 mK, which is roughly three orders of magnitude lower than the exchange interaction of the quantum AFM chain.

Weyl fermions and spin dynamics of metallic ferromagnet SrRuO3.

Weyl fermions that emerge at band crossings in momentum space caused by the spin-orbit interaction act as magnetic monopoles of the Berry curvature and contribute to a variety of novel transport phenomena such as anomalous Hall effect and magnetoresistance. However, their roles in other physical properties remain mostly unexplored. Here, we provide evidence by neutron Brillouin scattering that the spin dynamics of the metallic ferromagnet SrRuO3 in the very low energy range of milli-electron volts is closely relevant to Weyl fermions near Fermi energy.

Possibility of charge density wave transition in a SrPt2Sb2 superconductor.

The first-order transition at T(0) =  270 K for the platinum-based SrPt2Sb2 superconductor was investigated using x-ray diffraction and magnetic susceptibility measurements. When polycrystalline SrPt2Sb2 was cooled down through T(0), the structure was transformed from monoclinic to a modulated orthorhombic structure, and no magnetic order was formed, which illustrates the possibility of a charge density wave (CDW) transition at T(0). SrPt2Sb2 can thus be a new example to examine the interplay of CDW and superconductivity in addition to SrPt2As2, BaPt2As2, and LaPt2Si2.

Magnetic properties of the Ag-In-rare-earth 1/1 approximants.

We have performed magnetic susceptibility and neutron scattering measurements on polycrystalline Ag-In-RE (RE, rare-earth) 1/1 approximants. In the magnetic susceptibility measurements, for most of the RE elements, inverse susceptibility shows linear behaviour in a wide temperature range, confirming well localized isotropic moments for the RE(3 + ) ions. Exceptionally for the light RE elements, such as Ce and Pr, nonlinear behaviour was observed, possibly due to significant crystalline field splitting or valence fluctuation.