The phase transformation and magnetic properties of manganese bismuthide have been reinvestigated with single crystal samples of low temperature phase (LTP) and high temperature phase (HTP) in the quenched state (QHTP). It was established that the LTP and HTP are separate compounds with the chemical formulae MnBi and Mn 1.08 Bi respectively. The ferro-to-paramagnetic transition upon heating to 628 K and para-to-ferromagnetic transition upon cooling to 613 K correspond respectively to the phase decomposition of MnBi → Mn 1.08 Bi + Bi and Mn 1.08 Bi → MnBi + Mn. The effects of these transformations were also investigated in thin film specimens and the distribution of each phase in the thin films was determined. Magnetic properties of the LTP, HTP and QHTP obtained from the single crystals were compared to the previous data obtained from polycrystalline samples or thin films. For the QHTP single crystals, the saturation magnetization, M s , at 4 K is 3.04 μ B per Mn atom. This is 86% of the M s of the LTP. At 300 K we find M s to be 1.8 times larger than previously reported. The anisotropy energy K in the QHTP was found to be much larger than that of the LTP.

The phase transformation and physical properties of the MnBi and Mn 1.08 Bi compounds

Cloud water chemistry and the production of sulfates in clouds

The first self-consistent spin-polarised band-structure calculation of the ferromagnetic compound MnBi in its low-temperature phase has been performed. The spin-orbit interaction was treated as a perturbation using scalar-relativistic wavefunctions. On the Mn atoms an effective 3d5.5 configuration is found, with a magnetic moment of 3.6 mu B. A part of the d electrons is rather delocalised and strongly hybridised with Bi 6p states. This leads to a low density of states at the Fermi level in agreement with experiment. The calculated band structure is very similar to that of MnSb. The physical properties of both compounds are compared, and the dependence of the band structure on the direction of the spin magnetic moment is discussed in relation to the magnetic anisotropy and the magneto-optical polar Kerr effect.

http://iopscience.iop.org/article/10.1088/0305-4608/15/10/009/pdf

The electronic structure of MnBi

Chemical characterization of acid precipitation in Albany, New York

Sulfate and nitrate chemistry in cumuliform clouds

Single crystals of MnSb with various Mn compositions in e phase were prepared successfully with Bridgeman method. Magnetization and torque measurements were made on these crystals in temperatures ranging from 4.2°K to 800°K. The temperature dependence of saturation magnetization on the sample with 48.2 at. % Mn was in good agreement with Brillouin function of J =3/2∼2, but the samples with Mn rich composition exhibited slight discrepancies from this function. The saturation magnetization per Mn atom at 0°K in Bohr magneton decreases with increasing Mn composition, and these values are well explained quantitatively as excess Mn atoms with 2.2µ B occupy the B site and these spins are arranged antiparallel to those of A site Mn with 3.5µ B . The temperature dependences of the first order crystal magnetic anisotropy of various Mn compositions exhibit analogous function with those of cobalt and nickel derived from Carr's theory.

Crystal Magnetic Anisotropy and Magnetization of MnSb

A radio astronomy telescope with a wide field of view is an efficient tool for locating such transient radio sources in space as supernova explosions. A promising method of designing this type of telescope is to apply Fourier transformation to the output signals from a phased array antenna. the implementation of a high-speed parallel FFT processor to an eight-element linear phased array antenna output is reported in this paper. Small size and low-power con sumption are achieved by utilizing conventional digital video signal processing LSIs. In the present pilot system, arithmetic operation up to a speed of 2.7 COPS (giga operations per second) has been attained. the basic operation has been confirmed by solar observation.

Toshimichi Okita

Papers

Crystal Magnetic Anisotropy and Magnetization of MnSb

A high‐speed parallel FFT‐processor for a radio astronomy telescope