S. H. Rhim

Jahn-Teller driven perpendicular magnetocrystalline anisotropy in metastable ruthenium

Physics phenomena originating from spin-orbit interac-tions, such as magnetocrystalline anisotropy (MCA), Rashba-type interactions, or topological insulators, have attractedhuge attention for their intriguing physics as well as theirgreatpotentialforspintronicsapplications[1–5].Inparticular,MCA, where one particular direction of the magnetizationis energetically preferred, offers opportunities in spintronicssuch as magnetic random access memory (MRAM), spin-transfer torque (STT), magneto-optics, to list a few. Withrecent advances in fabrication techniques, the search formaterials with large MCA, more preferably, perpendicularMCA (PMCA), has been very intensive.In particular, ferromagnetic films that can provide PMCAare indispensable constituents in STT memory that utilizesspin-polarized tunneling current to switch magnetization [6].Two criteria have to be satisfied for the practical usage ofhigh-density magnetic storage: low switching current (

Formation of nitrogen-vacancy complexes during plasma-assisted nitrogen doping of epitaxial graphene on SiC(0001)

Doping epitaxial graphene on SiC(0001) using nitrogen plasma leads to N-vacancy complexes. Based on the calculated energetics by density functional theory and comparison with scanning tunneling microscopy observations, the most probable configuration is determined to be a nonmagnetic complex consisting of substitutional nitrogen next to a carbon vacancy. Further calculations show that other N-vacancy complexes, where the substituted N and the vacancy are the second and third nearest neighbors, do exhibit localized moments. These results indicate that the electronic and magnetic properties of graphene can be further tailored by plasma-assisted nitrogen doping.

Engineering of magnetostriction in Fe3Pt1−xIrx by controlling the Ir concentration

A tremendous change in both the sign and magnitude of magnetostriction (λ001) in Fe3Pt1−xIrx (x=0–1.0) was discovered through a first-principles study using the highly precise full-potential linearized augmented plane wave method. The obtained λ001 values span a wide range from −1050 (x=0) to +2670 ppm (x=0.25), a significantly large enhancement over the λ001 values attained for Galfenol, a widely investigated material. Further analysis confirmed that this large effect originates mainly from the nonmagnetic Ir and Pt with induced moments, of which the 5d orbital has larger spin–orbit coupling than the 3d orbital of Fe.

Origin of p-type characteristics in a SnSe single crystal

SnSe single crystals have recently been found to exhibit excellent thermoelectric performance with an extremely high figure of merit (ZT) value of 2.6. Although this high ZT value has attracted considerable attention, the microscopic origin of the p-type characteristics of SnSe is not yet clearly understood. Here, we directly observed and identified intrinsic point defects existing on SnSe via scanning tunneling microscopy (STM) and investigated the effect of defects on the electronic properties using density functional theory (DFT) calculations. Our results demonstrate that the most dominant Sn vacancies move the Fermi energy inside the dispersive valence band and produce extra holes throughout the system. On the other hand, Se vacancies create a nondispersive donor level and generate immobile electrons localized near the vacancy site. Our combined STM/DFT studies show that the p-type characteristics of SnSe originate from extra holes in the dispersive Bloch-like band created by Sn vacancies. We expect t...

Theory of perpendicular magnetocrystalline anisotropy in Fe/MgO (001)

Abstract The origin of large perpendicular magnetocrystalline anisotropy (PMCA) in Fe/MgO (001) is revealed by comparing Fe layers with and without the MgO. Although Fe-O p-d hybridization is weakly present, it cannot be the main origin of the large PMCA as claimed in previous study. Instead, perfect epitaxy of Fe on the MgO is more important to achieve such large PMCA. As an evidence, we show that the surface layer in a clean free-standing Fe (001) dominantly contributes to EMCA, while in the Fe/MgO, those by the surface and the interface Fe layers contribute almost equally. The presence of MgO does not change positive contribution from 〈 xz | l Z | yz 〉 , wherease it reduces negative contribution from 〈 z 2 | l X | yz 〉 and 〈 xy | l X | xz , yz 〉 .

Surface-termination-dependent magnetism and strong perpendicular magnetocrystalline anisotropy of an FeRh(001) thin film

Magnetism of FeRh (001) films strongly depends on film thickness and surface terminations. While magnetic ground state of bulk FeRh is G-type antiferromagnetism, the Rh-terminated films exhibit ferromagnetism with strong perpendicular MCA whose energy +2.1 meV/

Strain effect on electronic structure and thermoelectric properties of orthorhombic SnSe: A first principles study

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Anisotropic thermal conductivity of semiconducting graphene monoxide

is two orders of magnitude greater than 3

Magnetocrystalline anisotropy of 4d/5d transition metals on a Co(0001) surface: A first-principles study

d

First-principles studies on infrared properties of semiconducting graphene monoxide

magnetic metals, where