Structural and magnetic properties of MBE-grown GeMnN2thin films

Abstract

Abstract:Epitaxial GeMnN 2 thin films are synthesized by plasma-assisted molecular beam epitaxy.Transmission electron microscopy and x-ray diffraction measurements confirm that it is the orthorhombic variant, consistent with the predictions of first-principles calculations. The magnetic properties of the films are related to defects, with samples grown under Ge-rich conditions exhibiting a net magnetic moment above room temperature. These results are explained by first-principles calculations, indicating that the preferential substitution of one magnetic sublattice of GeMnN 2 by impurities and/or intrinsic defects such as Ge antisites produces a net magnetic moment in an antiferromagnetic background and also introduces spinpolarized carriers near the Fermi level.

Combinatorial Synthesis of Cation-Disordered Manganese Tin Nitride MnSnN2 Thin Films with Magnetic and Semiconducting Properties

“…The deposition chamber, which is largely made of steel components, may be the source of such an impurity, although the samples measured were not in direct contact with these components. However, similar net moments were observed in thin films of MnGeN 2 and were attributed to cation site disorder . Above T * (e.g., at T = 40 K), the linear behavior is consistent with paramagnetism.…”

“…However, similar net moments were observed in thin films of MnGeN 2 and were attributed to cation site disorder. 20 Above T* (e.g., at T = 40 K), the linear behavior is consistent with paramagnetism. The traces do not plateau at high fields, indicating that the magnetic moment is not saturated at μ 0 H = ±7 T. To probe the possibility of spin-glass behavior, we performed AC susceptibility measurements, but the signal was below the instrumental sensitivity limit.…”

“…They are structurally analogous to GaN, suggesting the possibility of AFM spintronic integration into III–N-based device stacks. In this vein, Liu et al synthesized MnGeN 2 thin films by using molecular-beam epitaxy, although the magnetic properties varied between paramagnetic and ferrimagnetic depending on composition and substrate . This discrepancy in properties between bulk and thin film MnGeN 2 shows that much remains to be learned about the fundamental chemistry and physics of these materials.…”

“…As for magnetism, cation disorder tends to disrupt the long-range interactions that result in magnetic ordering, lowering transition temperatures . Cation order in bulk syntheses of MnSiN 2 and MnGeN 2 (which exhibited high temperature antiferromagnetism) was clearly identified with X-ray and neutron diffraction on powder samples. ,, In contrast, evidence for cation ordering in the MBE-grown thin films of MnGeN 2 (which exhibited paramagnetic or ferrimagnetic behavior) is insufficient . Therefore, careful studies linking composition, (dis)­order, and properties are need to better understand the magnetic and semiconducting behavior of Mn–IV–N 2 systems.…”

“…In this vein, Liu et al synthesized MnGeN 2 thin films by using molecular-beam epitaxy, although the magnetic properties varied between paramagnetic and ferrimagnetic depending on composition and substrate. 20 This discrepancy in properties between bulk and thin film MnGeN to be learned about the fundamental chemistry and physics of these materials. For example, composition and cation disorder are known to affect properties like bandgap and magnetic transitions, 21,22 but these variables have not yet been systematically studied in the Mn−IV−N 2 system.…”