Crystalline phase and orientation control of manganese nitride grown on MgO(001) by molecular beam epitaxy

Abstract

Structural and magnetic characterizations of Mn2CrO4 and MnCr2O4 films on MgO(001) and SrTiO3(001) substrates by molecular beam epitaxy J. Appl. Phys. 109, 07D714 (2011); 10.1063/1.3545802Structural characteristics and magnetic properties of λ-MnO 2 films grown by plasma-assisted molecular beam epitaxyThe phase and orientation of manganese nitride grown on MgO͑001͒ using molecular beam epitaxy are shown to be controllable by the manganese/nitrogen flux ratio as well as the substrate temperature. The most N-rich phase, phase ͑MnN͒, is obtained at very low Mn/N flux ratio. At increased Mn/N flux ratio, the next most N-rich phase, the phase ͑Mn 3 N 2 ͒, is obtained having its c axis normal to the surface plane. Further increasing the Mn/N flux ratio, the phase ͑Mn 3 N 2 ͒ having its c axis in the surface plane is obtained. Finally, the phase ͑Mn 4 N͒ is obtained at yet higher Mn/N flux ratio. The structural phase variation with Mn/N flux ratio is due to the kinetic control of the surface chemical composition, which determines the energetically most favorable phase. For a given Mn/N flux ratio, the phase is also found to be a function of the substrate temperature, with the less N-rich phase occurring at the higher substrate temperature. The change of phase with temperature is attributed to the change in the chemical composition resulting from the diffusion of N vacancies. Since the magnetic properties of Mn x N y depend on the phase, the Mn/N flux ratio provides a way of directly controlling the magnetic properties. A phase diagram for molecular beam epitaxial growth is presented.

Atomic-scale structure of η-phase Mn3N2(010) studied by scanning tunneling microscopy and first-principles theory

“…8 The RHEED pattern of the Mn 3 N 2 film is streaky, indicating epitaxial growth. 7,8 Following growth, the samples are investigated with in situ STM. For normal STM studies, we use electrochemically etched tungsten tips which are cleaned in the ultra high vacuum chamber using electron bombardment.…”

“…The growth rate is proportional to the measured Mn flux, which is Flux Mn = 3.2×10 14 cm −2 s −1 , resulting in a growth rate of ∼ 35Å/min; typical film thickness is ∼ 2000-3000Å. 8 The RHEED pattern of the Mn 3 N 2 film is streaky, indicating epitaxial growth. 7,8 Following growth, the samples are investigated with in situ STM.…”

“…The control of the phases, and therefore the magnetic properties and orientations of manganese nitride grown on MgO(001) using molecular beam epitaxy (MBE), was reported by Yang et al recently. 7,8 The epitaxially grown phases can be controlled by the ratio of manganese to nitrogen and the substrate temperature. We have also recently investigated the surface magnetic structure of η-Mn 3 N 2 (010) using atomic-scale spin-polarized scanning tunneling microscopy (SP-STM).…”

“…[1][2][3][4][5][6][7][8][9][10] Manganese nitride (Mn-N) is interesting due to its magnetic properties. It is known from previous bulk studies that manganese nitride has different bulk phases, including θ (MnN), η (Mn 3 N 2 ), ε (Mn 4 N), and ζ (Mn 5 N 2 , Mn 2 N, and Mn 2 N 0.86 ).…”

Enhancement of magnetic properties by nitrogen implantation to Mn-implanted p-type GaN

“…The Mn-N compounds are antiferromagnetic materials with a Néel temperature above 300 K, reducing the magnetic moment of the Mn-implanted GaN. 12,13 The enhancement of magnetic properties by N implantation to Mn-implanted GaN originated from the Ga-Mn bond ͓Fig. 3͑b͔͒, even though such phases were not identified from XRD measurements ͑Fig.…”