Search for half-metallic antiferromagnetism using pulsed magnetic fields:: experimental investigation of Mn3Si, CuMnSb and PdMnTe

A comparison of the suppression of antiferromagnetism in metals as a function of temperature or high magnetic fields provides a deep probe of the nature of the metallic state as well as the antiferromagnetic order. Here we report magnetization and resistivity measurements of the metallic antiferromagnets Mn3Si (T-N = 25 K), CuMnSb (T-N = 50 K) and PdMnTe (T-N = 17 K) in pulsed magnetic fields up to mu(0)H=50 T and temperatures down to 4.2 K. Experiments were performed at the Dresden high magnetic field facility. The low antiferromagnetic ordering temperatures in these compounds combined with the ordered magnetic moments known from neutron scattering studies show that we access for the first time equivalent magnetic and thermal energy scales in transition metal antiferromagnets. While Mn3Si and CuMnSb exhibit a bulk magnetization of only a fraction of the ordered moment up to 50 T, PdMnTe shows a trend towards saturation. We speculate that in particular the tiny response of Mn3Si and CuMnSb up to 50 T are related to a strong asymmetry of the density of majority to minority charge carriers. Such a trend would be naturally supported in the Heusler structure of these compounds as originally proposed for NiMnSb and PtMnSb, in which the absence of minority charge carriers is referred to as half-metallic ferromagnetism. (C) 2004 Elsevier B.V. All rights reserved.