Abstract
The peculiar magnetic properties of rare earth nitrides (RENs) make them suitable for a wide range of applications. Here, we report on a density functional theory (DFT) study of an interesting member of the family, two-dimensional (2D) NdN film, using the generalized gradient approximation (GGA), including the Hubbard (U) parameter. We consider different film thicknesses, taking into account the effects of N vacancies (VN) and dopants (C and O). Formation energy values show that, even though N vacancy is the predominant defect, C and O dopants are also probable impurities in these films. Individual Nd and N magnetic moments oscillate in the presence of VN and dopants owing to the induced lattice distortions. The density of states calculations show that the 2D NdN film has a semi-metallic nature, while the f orbitals are separated into fully filled and empty bands. A magnetic anisotropy energy of ∼50 μeV is obtained, and the easy axis aligns along the film orientation as the film thickness increases, revealing that such films are ideal candidates for spintronic applications.
Highlights
Elements in the rare-earth nitride (REN) family are interesting from both a fundamental and a practical point of view, owing to their partially occupied 4f sub-shell, which in turn leads to peculiar magnetic and electronic properties.[1,2,3,4,5,6] The resulting ferromagnetic (FM) and diverse conducting properties, ranging from half-metallic through insulating to semi-metallic, make them attractive candidates for spintronic devices,[5] which contrasts with dilute magnetic semiconductors (DMS)
While the magnetic and electronic properties of DMS materials are primarily governed by the presence of dopants or defects,[7,8,9,10,11,12] RENs do not require doped foreign atoms or large hole concentrations to generate magnetic interactions.[5,13]
Since large magnetic anisotropy energy (MAE) value is essential for spintronic applications to avoid the spin ip transition, these results indicate that 2D NdN lms are promising candidates for data storage as well as for other potential smart magnetic applications, as its MAE can be tuned by varying the number of layers
Summary
Elements in the rare-earth nitride (REN) family are interesting from both a fundamental and a practical point of view, owing to their partially occupied 4f sub-shell, which in turn leads to peculiar magnetic and electronic properties.[1,2,3,4,5,6] The resulting ferromagnetic (FM) and diverse conducting properties, ranging from half-metallic through insulating to semi-metallic, make them attractive candidates for spintronic devices,[5] which contrasts with dilute magnetic semiconductors (DMS). While the magnetic and electronic properties of DMS materials are primarily governed by the presence of dopants or defects,[7,8,9,10,11,12] RENs do not require doped foreign atoms or large hole concentrations to generate magnetic interactions.[5,13] RENs are the only stable elements whose f orbitals are more than marginally lled, leading to large spin and orbital moments Taking advantage of these characteristics, RENs have been extensively studied, aiming to identify prototypical spintronic devices.[5] For example, the possibility of obtaining a GdNbased spin lter has been reported.[14] Apart from magnetic properties, the electronic and transport properties of RENs present many ambiguities.[5,13] Even for compounds having similar structures, insulating to metallic behavior was reported,[5] which was attributed to the highly reactive nature of these materials and the ease with which nitrogen vacancies form.[5]. The spin-orbit coupling (SOC) effects are included in calculations to estimate the spin and orbital contribution to magnetism as well as to determine axis preference of magnetization
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