Jihun Shim

A theoretically designed van der Waals ferromagnet Fe 4 GeTe 2 is synthesized and shows the nearly room temperature ferromagnetism.

We address the fundamental question of crossover from the localized to the itinerant state of a paradigmatic heavy fermion material: CeIrIn5. The temperature evolution of the one-electron spectra and the optical conductivity are predicted from first-principles calculation. The buildup of coherence in the form of a dispersive many-body feature is followed in detail, and its effects on the conduction electrons of the material are revealed. We find multiple hybridization gaps and link them to the c

We have investigated electronic structures of a newly discovered antiperovskite superconductor ${\mathrm{MgCNi}}_{3}$ and related compounds ${\mathrm{MgBNi}}_{3}$ and ${\mathrm{MgNNi}}_{3}.$ In ${\mathrm{MgCNi}}_{3},$ a peak of very narrow and high density of states is located just below the Fermi level, which corresponds to the ${\ensuremath{\pi}}^{*}$ antibonding state of Ni $3d$ and C $2p$ but with the predominant Ni $3d$ character. The prominent nesting feature is observed in the $\ensuremat

We demonstrated the synthesis of a conductive two-dimensional metal-organic framework (MOF) thin film by single-step all-vapor-phase chemical vapor deposition (CVD). The synthesized large-area thin film of Cu₃(C₆O₆)₂ has an edge-on-orientation with high crystallinity. Cu₃(C₆O₆)₂ thin film-based microdevices were fabricated by e-beam lithography and had an electrical conductivity of 92.95 S/cm. Synthesis of co

We explored how to improve the thermoelectric properties of the layered transition-metal dichalcogenides 2H-MQ 2 (M = Mo, W; Q = S, Se, Te) by comparing the thermoelectric properties of hypothetical mixed-layer systems 2H-MQ 2 /2H-MQ′ 2, in which two different layers 2H-MQ 2 and 2H-MQ′ 2 (Q, Q′ = S, Se, Te) alternate, with those of their pure components on the basis of density functional calculations. Our study predicts that the mixed-layer compounds MS 2 /MTe 2 (M = Mo, W) strongly enhance the

Our calculations show that, when doped by electrons, the organic–inorganic perovskite iodides ABI₃(A = CH₃NH₃, NH₂CHNH₂; B = Sn, Pb) can be a good thermoelectric material with thermoelectric efficiency comparable to that of hole-doped Bi₂Te₃.

Finding alternatives for Bi2Te3, the only thermoelectric material for near-room-temperature (RT) applications, is of great importance in thermoelectrics. Here, we report a very promising near-RT thermoelectric figure of merit (ZTmax = 0.9 at 390 K, ZTave = 0.68 between RT and 390 K) for Cu-excess α-Cu2+xSe, comprising low-cost, abundant, and nontoxic elements. Although α-Cu2+xSe has a propensity to form a large number of Cu vacancies to stabilize its structure by diminishing Cu–Cu interactions,

Significance The temperature ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>T</mml:mi> </mml:math> )-dependent evolution of the Kondo lattice electronic structure is a long-standing topic of theoretical and experimental investigation, still lacking a truly microscopic theory that agrees with a full experimental characterization. Here multiple characteristic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>T</mml:mi> </mml:

The Dirac fermions of Sb square net in AEMnSb2 (AE=Sr, Ba) are investigated by using first-principles calculation. BaMnSb2 contains Sb square net layers with a coincident stacking of Ba atoms, exhibiting Dirac fermion behavior. On the other hand, SrMnSb2 has a staggered stacking of Sr atoms with distorted zig-zag chains of Sb atoms. Application of hydrostatic pressure on the latter induces a structural change from a staggered to a coincident arrangement of AE ions accompanying a transition from

We have investigated the electronic properties and hole mobilities of picene and its isomer pentacene using the density functional theory and classical Marcus charge transfer theory. In pristine crystal with herringbone structure, pentacene and picene have drift hole mobilities of 2.147 and 0.644 cm 2 V –1 s –1, respectively, which are consistent with recent experimental results. We also show that picene crystal can exhibit maximum mobility up to 2.629 cm 2 V –1 s –1 along the π–π stacking direc

Abstract Discovery of two dimensional (2D) magnets, showing intrinsic ferromagnetic (FM) or antiferromagnetic (AFM) orders, has accelerated development of novel 2D spintronics, in which all the key components are made of van der Waals (vdW) materials and their heterostructures. High-performing and energy-efficient spin functionalities have been proposed, often relying on current-driven manipulation and detection of the spin states. In this regard, metallic vdW magnets are expected to have severa

In this article we report point defect-assisted doping mechanism and related thermoelectric transport properties in Pb-doped BiCuOTe compounds.

Abstract Magnetic anisotropy energy (MAE) is one of the most important properties in two-dimensional magnetism since the magnetization in two dimension is vulnerable to the spin rotational fluctuations. Using density functional theory calculation, we show that perpendicular electric field dramatically enhances the in-plane and out-of-plane magnetic anisotropies in Fe 3 GeTe 2 and Fe 4 GeTe 2 monolayers, respectively, allowing the change of easy axis in both systems. The changes of the MAE under