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

Abstract

We report on structural, magnetic, transport, and spin-polarization measurements of the Heusler alloys ${\mathrm{Co}}_{2}\mathrm{MnSi}$ and NiMnSb. Laue diffraction patterns confirm the single-crystal nature of ${\mathrm{Co}}_{2}\mathrm{MnSi}.$ Room-temperature transport measurements show a negative magnetoresistance in NiMnSb. Point-contact Andreev reflection measurements of the spin polarization yield polarization values for ${\mathrm{Co}}_{2}\mathrm{MnSi}$ and NiMnSb of 56% and 45%, respectively. Temperature dependence of resistivity for ${\mathrm{Co}}_{2}\mathrm{MnSi}$ reveals a relatively large residual resistivity ratio $({\ensuremath{\rho}}_{293\mathrm{K}}/{\ensuremath{\rho}}_{5\mathrm{K}})$ typical of single-crystal Heusler alloys. In NiMnSb, resistivity and magnetization as a function of temperature show evidence of a magnetic phase transition near 90 K.