Phase Separation Of Antiferromagnetism Research Articles

Phase separation of antiferromagnetism and superconductivity in Rb x Fe2−y Se2 observed by using Rb NMR

We have carried out 87Rb NMR measurements on single crystals with and without the superconducting (SC) transition to clarify whether the SC and the antiferromagnetic (AFM) states are microscopically coexistent or just phase-separated in the Rb-intercalated iron-selenide Rb x Fe2−y Se2. The 87Rb NMR spectra observed at temperature below 300 K for these crystals are clearly separable into two parts with different structures and widths. The broader spectrum can be explained by the presence of a region with an AFM spin structure proposed by neutron scattering studies. The narrower spectrum in the crystal with the SC transition can be understood from the temperature dependences of the spectral frequency-position and shape to stem from the SC region with T c = 30.8 K. Thus, we can clearly conclude that the superconductivity and the antiferromagnetism in the present system are phase-separated. Also, the crystal without the SC transition has two phase-separated regions with respective magnetic transitions at ∼500 and ∼50 K.

Resistive switching phenomenon driven by antiferromagnetic phase separation in an antiperovskite nitride Mn3ZnN

A resistive-switching phenomenon driven by antiferromagnetic phase separation is observed for a manganese nitride Mn3ZnN, which crystallizes in the antiperovskite structure. Measurements of the lattice parameters, magnetic susceptibility, electrical resistivity, and specific heat from 2 K to 300 K reveal antiferromagnetic phase separation that appears below a temperature of approximately 190 K. The mechanism of the phase separation is highly complicated; nevertheless the accompanying resistive-switching phenomenon is useful for non-volatile memory applications.

Neutron diffraction and X-ray absorption study of CaMn0.6Ru0.4O3

Abstract Neutron diffraction and X-ray absorption measurements were carried out for a perovskite ferromagnet, CaMn0.6Ru0.4O3. While a previous X-ray diffraction had shown an orthorhombic Pnma structure, the present neutron diffraction at room temperature provided a better result for monoclinic P21/n. The analysis for the pattern at 4 K was consistent with the ferro- and antiferromagnetic phase separation at low temperatures. An X-ray absorption spectrum at the Ru–K edge showed that the valence of Ru is higher than 4+, which supports the proposed valency effect.