Structural and magnetic transitions in cubic Mn₃Ga

Abstract

The structural, magnetic and electron-transport properties of cubic Mn3Ga have been investigated. The alloys prepared by arc melting and melt-spinning show an antiferromagnetic spin order at room temperature but undergo coupled structural and magnetic phase transitions at 600 and 800 K. First-principles calculations show that the observed magnetic properties are consistent with that of a cubic Mn3Ga crystallizing in the disordered Cu3Au-type structure. The samples exhibit metallic electron transport with a resistance minimum near 30 K, followed by a logarithmic upturn below the minimum. The observed anomaly in the low-temperature resistivity has been discussed as a consequence of electron scattering at the low-lying excitations of the structurally disordered Mn3Ga lattice.

Structure, Magnetic Properties, and Coercivity Mechanism of Rapidly Quenched Mn_{<italic>x</italic>}Ga Ribbons

“…Therefore, the Curie temperature of D0 22 -Mn 3 Ga cannot be determined because of the occurrence of structure transition at temperature below the magnetic phase transition. The observed structure transition is in agreement with recent studies which were confirmed in temperature-dependent XRD studies, differential scanning calorimetry and temperature dependence of magnetization [7], [15], [16]. Nevertheless, both samples with high transition temperature are very suitable for application at and above room temperature.…”

Synthesis and magnetism of single-phase Mn-Ga films

“…16. This type of low-temperature resistivity behavior has been observed in other Mn-based magnetic alloys such as disordered cubic Mn 3 Ga. 11 Both samples show positive and small magnetoresistance (0.7% at room temperature). This may be attributed to the spin disorder due to competing ferro-and antiferromagnetic interactions present in the films.…”

“…4(c). 11,16 The values of the residual resistivity ratio (RRR) defined as q 305 K /q 2 K for the Mn 2 Ga 5 and Mn 3 Ga films are close to one, indicating that the films have substantial structural disorder which would produce spin disorder because of likely antiferromagnetic Mn-Mn interactions. If the low-temperature spin structure has spin-glass-like feature, the conduction electrons may exhibit scattering from a nearly degenerate two-level system as suggested in Ref.…”

“…1(c). We note that Mn 3 Ga can be stabilized in a hexagonal structure if it is cooled from a temperature exceeding 830 K, although the tetragonal phase is the most stable one and is obtained by a lowtemperature heat treatment between 725 K and 825 K. 11 We have obtained the tetragonal Mn 3 Ga by reannealing the in situ annealed sample at 800 K for 2 h. All films are a)…”

Transition from Anomalous Hall Effect to Topological Hall Effect in Hexagonal Non-Collinear Magnet Mn3Ga

“…It has been reported to have tetragonal, hexagonal and face-centered cubic crystal structures when subjected to different heat treatments 2–4 . Hexagonal Mn 3 Ga (70–74 at.% Mn) has a D0 19 -type structure with space group P63/mmc 5 , as shown in Fig.…”