The evolution of magnetic transitions, negative thermal expansion and unusual electronic transport properties in Mn3AgxMnyN

• Two distinct magnetic transitions at TN and lower temperature affected by doping were discussed.
• The broadened negative thermal expansion behavior was observed in Mn3AgxMnyN.
• All compounds show nearly zero temperature coefficient of resistivity behavior.
• Tunable values of temperature coefficient of resistivity were obtained.

The antiperovskite compounds Mn3AgxMnyN with Ag vacancies and Mn doping at Ag site were synthesized and investigated. The introduction of Ag vacancies has a very small influence on magnetic transitions. However, the magnetic transitions at TN (Néel temperature) and Tt (transition at lower temperature) gradually overlap with Mn doping accompanied by broadening of negative thermal expansion behavior. We also observed the nearly zero temperature coefficient of resistivity (NZ-TCR) behavior above magnetic order–disorder transition. The tunable TCR values from positive to negative could be achieved in Mn3AgxMnyN by reducing the contribution of (electron–phonon) e–p scattering in resistivity. Our results reveal the significance of e–p scattering for the evolution of TCR values, which could enrich the understanding of NZ-TCR behavior in antiperovskite manganese nitrides.