The antiperovskite compound Mn3 Cu1-x Gex N with x∼0.5 has a giant negative thermal expansion coefficient due to the magnetovolume effect near room temperature. Competition between the Γ5g and Γ4g antiferromagnetic structures around the magnetic ordering temperature could be the driving force for such a phenomenon. In order to examine this possibility, we performed neutron-diffraction experiments on Mn3Cu0.5Ge0.5N and N 14 nuclear magnetic resonance experiments on Mn3 Cu0.6 Ge0.4 N. As a reference material, we also investigated Mn3 NiN, whose spin structure is represented by a linear combination of the Γ5g and Γ4g antiferromagnetic components. We conclude that in Mn3 Cu 1-x Gex N (x∼0.5), the Γ4g antiferromagnetic component is nearly absent and the competition between the Γ5g and Γ4g antiferromagnetic structures is irrelevant to the giant negative thermal expansion coefficient. The Γ5g antiferromagnetic ordered moment gradually develops with decreasing temperature. This provides a thorough justification for the analysis presented in the previous letter.
|Physical Review B - Condensed Matter and Materials Physics
|Published - Jun 14 2010
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics