Structural, magnetic, and electrical properties of collinear antiferromagnetic heteroepitaxy cubic Mn3Ga thin films

Abstract

Although a cubic phase of Mn3Ga with an antiferromagnetic order has been theoretically predicted, it has not been experimentally verified in a bulk or film form. Here, we report the structural, magnetic, and electrical properties of antiferromagnetic cubic Mn3Ga (C-Mn3Ga) thin films, in comparison with ferrimagnetic tetragonal Mn3Ga (T-Mn3Ga). The structural analyses reveal that C-Mn3Ga is heteroepitaxially grown on MgO substrate with the Cu3Au-type cubic structure, which transforms to T-Mn3Ga as the RF sputtering power increases. The magnetic and magnetotransport data show the antiferromagnetic transition at TN = 400 K for C-Mn3Ga and the ferrimagnetic transition at TC = 820 K for T-Mn3Ga. Furthermore, we find that the antiferromagnetic C-Mn3Ga exhibits a higher electrical resistivity than the ferrimagnetic T-Mn3Ga, which can be understood by spin-dependent scattering mechanism.

Epitaxial growth of the cubic L21-Mn2.6Ga Heusler alloy on MgO(001)

“…PLEASE CITE THIS ARTICLE AS DOI: 10.1063/5.0001349 evaluate the Curie temperature (TC) of the films. The curve shows a monotonically decreasing magnetization with increasing temperature, and the TC is higher than 400 K.Ref 15. reported TC = 800 K for tetragonal Mn3Ga.In summary, we have grown epitaxial Mn2.6Ga thin films on MgO(001)substrates with different thicknesses.…”

“…PLEASE CITE THIS ARTICLE AS DOI: 10.1063/5.0001349 deposition rate appears to be important in promoting the epitaxial reorientation, and increasing the deposition rate suppresses the (111) peak in 50 nm thick films. Bang et al 15 also found that the cubic phase was favored at lower growth rates but transitioned to mixed then tetragonal films at higher growth rates and lower Mn content.…”

“…13 A random distribution of the Mn and Ga atoms converts the unit cell of the D022 structure into two cubic unit cells of the disordered L21 antiferromagnetic phase. The L21 disordered fcc Mn3Ga with lattice constant a = 3.84 Å has been reported to be antiferromagnetic (AFM) with Néel temperature of 400 K. 14,15 Early theoretical calculations show that the cubic structure is a transition phase during the transformation from tetragonal to hexagonal phases. 16 Few works report the formation of this phase experimentally.…”

“…The ribbons have thermal stability up to 350 °C, and above this temperature a transformation to the tetragonal-D022 and to the hexagonal-D019 phases is observed upon thermal annealing at 500 and 600 °C, respectively. Recently, Bang et al 15 reported the growth of L21-Mn3Ga thin films by varying the power during magnetron sputtering. The cubic AFM phase is achieved only when the samples contain a Mn excess in the range 1-10 at.%.…”

“…The cubic AFM phase is achieved only when the samples contain a Mn excess in the range 1-10 at.%. 15 The AFM ordering arises from stacking alternating ferromagnetic (FM) planes along the c axis. The same authors reported that L21-Mn3Ga thin films have poor metallic conductivity.…”