Half-metallic ferromagnets. I. Structure and magnetic properties of NiMnSb and related inter-metallic compounds

Abstract

The authors present investigations of the crystal structure the microstructure and the magnetic properties of the inter-metallic compounds XMnSb (X=Pt, Ni, Co, Au, Cu) and PtMnSn. It was found that several of these materials contain precipitates of other phases and/or large atomic disorder, which can be influenced by heat treatment. The magnetic properties show an effective paramagnetic moment which differs from the value corresponding to the saturation moment at 0 K. This effect is attributed to a decrease of the conduction electron spin polarisation at high temperature.

Ab initio calculations and synthesis of the off-stoichiometric half-Heusler phase Ni1−xMn1+xSb

“…9 for T 1 =0 K, T 2 = 600 K, and T 3 = 1500 K, which is 100 K above the melting point of 1400 K for NiMnSb. 2,3 In order to estimate the amount of Mn that can be incorporated in the C1 b crystal structure by replacing Ni, we have drawn the Gibbs common tangent line to the curves corresponding to T = 600 K-which is a common sputter deposition temperature for NiMnSb. We find the left tangent point to be located at x = 0.32, which implies that up to 32% extra Mn can be incorporated in the C1 b structure without resulting in any secondary C38 crystal phase formation.…”

“…2 Several experimental studies on bulk samples including measurements of resistivity, Hall effect, and magnetic properties arrived at the conclusion that the ground state of NiMnSb is half-metallic. 2,3 This was supported by the positron-annihilation measurements of bulk spin-polarization by Hanssen et al 4 In contrast, surface sensitive techniques, such as superconducting point contact measurements ͑Andreev reflection 5 ͒ 6,7 and spin-resolved photoemission spectroscopy 8,9 have failed to reproduce spin-polarization beyond the extent of a normal ferromagnet, even at low temperature. Calculations indicate NiMnSb surfaces and interfaces not to be half-metallic in general but using a suitably chosen interface-such as ͑111͒ oriented CdS or InP-halfmetallicity can be restored.…”

Magnetic, structural, and transport properties of the Heusler alloysCo2MnSiand NiMnSb

“…7 and 8͒ and their high Curie temperatures of 985 K ͑Ref. 9͒ and 728 K, 10 respectively. In this paper, we present a study of basic structural, magnetic, and transport properties of NiMnSb and single-crystal Co 2 MnSi.…”

Distribution of Atoms on Crystallographic Positions in Heusler Alloys $M$MnSb ($M$ = Co, Ni, Cu) and Their Electronic Structure

“…Возможность такого типа атомных разупорядочений в NiMnSb подтверждается и экспериментом по нейтронной дифракции [9]. Далее, в рамках ни-чем не обоснованных предположений, в работе [10] сделан вывод о том, что рост электросопротивления сплавов MMnSb при последо-вательном переходе от сплавов с кобальтом к никель-и медьсодер-жащим соединениям обусловлен ростом в них степени разупорядо-ченности в положениях атомов.…”