A new noncollinear triangle antiferromagnetic phase in Mn3GaN by Cr doping

The study on spintronic materials with noncollinear antiferromagnetic (AFM) structures is a hot research field. Antiperovskite Mn-based compounds Mn3XN with Kagome lattice have attracted extensive attention, which display abundant physical properties. Particularly, some with non-zero Berry curvature can exhibit anomalous Hall effects or spin Hall effects despite their noncollinear AFM structures. They are expected to have potential applications in AFM spintronic devices. Here a new noncollinear triangle AFM phase besides the well-known Γ5g phase in Mn3GaN was observed with the space group of RI3‾c by Cr doping at Mn sites. By Neutron powder diffraction, the magnetic structure was determined. The spins of Mn at (111) plane in a Kagome lattice not only orient toward in-plane triangle center which is like Γ4g configuration, but also present out-plane rotation. As a result, a magnetic phase diagram was built. Correspondingly, the electronic transport property presents a different behavior accompanied by the transformation of magnetic phase from Γ5g into RI3‾c. And the thermal expansion behavior is tuned on account of the alteration of magnetic phase. Both the electronic transport property and the thermal expansion behavior in Mn3-xCrxGaN compounds correlate with the magnetic structures, indicating a strong coupling between spin-charge-lattice. The appearance of the new noncollinear triangle AFM phase in Mn3XN antiperovskite compounds will provide a possible way for exploring new AFM spintronic materials.