News

[Dowon Song and Prof. Kookrin Char] High-k perovskite gate oxide for modulation beyond 1014 cm-2 Mar 24, 2022 l Hit 220

Scaling down of semiconductor devices requires high-k dielectric materials to continue lowering the operating voltage of field-effect transistors (FETs) and storing sufficient charge on a smaller area. Here, we investigate the dielectric properties of epitaxial BaHf0.6Ti0.4O3 (BHTO), an alloy of perovskite ox...

[Dr. Suhan Son, Youjin Lee and Prof. Je-Geun Park] Multiferroic Enabled Magnetic‐exciton in 2D Quant... Jan 13, 2022 l Hit 285

Matter‐light interaction is at the center of diverse research fields from quantum optics to condensed matter physics, opening new fields like laser physics. A magnetic exciton is one such rare example found in magnetic insulators. However, it is relatively rare to observe that external variables control matter‐light in...

[Dongjin Oh and Prof. Changyoung Kim] B1g-Phonon Anomaly Driven by Fermi Surface Instability at Inte... Dec 30, 2021 l Hit 348

We performed temperature- and doping-dependent high-resolution Raman spectroscopy experiments on YBa2Cu3O7-δ to study B1g phonons. The temperature dependence of the real part of the phonon self-energy shows a distinct kink at T = TB1g above Tc due to softening, in addition to the one due to the onset of the super...

[Jae-Mo Lihm and Prof. Cheol-Hwan Park] Development of Wannier Function Perturbation Theory Dec 23, 2021 l Hit 413

Abstract: Thanks to the nearsightedness principle, the low-energy electronic structure of solids can be represented by localized states such as the Wannier functions. Wannier functions are actively being applied to a wide range of phenomena in condensed matter systems. However, the Wannier-function-based representation...

[Hyunsoo Ha, Prof. Bohm-Jung Yang] Colossal angular magnetoresistance in ferrimagnetic nodal-line se... Nov 25, 2021 l Hit 375

Efficient magnetic control of electronic conduction is at the heart of spintronic functionality for memory and logic applications1,2. Magnets with topological band crossings serve as a good material platform for such control, because their topological band degeneracy can be readily tuned by spin configurations, dramati...

[Dr. Tae Yun Kim and Prof. Cheol-Hwan Park] Magnetic anisotropy and magnetic ordering of transition-... Nov 25, 2021 l Hit 395

A magnetic model with an unprecedentedly large number of parameters was determined from first-principles calculations for transition-metal phosphorus trisulfides (TMPS3’s), reproducing the measured magnetic ground states of bulk TMPS3’s. Our Monte Carlo simulations for the critical temperature, magnetic sus...

[Sungjoon Park, Yoonseok Hwang, Hong Chul Choi/ Prof. Bohm-Jung Yang] Topological acoustic triple po... Nov 24, 2021 l Hit 278

Acoustic phonon is a classic example of triple degeneracy point in band structure. This triple point always appears in phonon spectrum because of the Nambu–Goldstone theorem. Here, we show that this triple point can carry a topological charge q that is a property of three-band systems with space-time-inversion sy...

[Yoonseok Hwang, Prof. Bohm-Jung Yang] Geometric characterization of anomalous Landau levels of isol... Nov 8, 2021 l Hit 409

According to the Onsager’s semiclassical quantization rule, the Landau levels of a band are bounded by its upper and lower band edges at zero magnetic field. However, there are two notable systems where the Landau level spectra violate this expectation, including topological bands and flat bands with singular ban...

[Dr. Taehun Kim, Prof. Je-Geun Park] Slow oxidation of magnetite nanoparticles elucidates the limits... Nov 8, 2021 l Hit 1074

Magnetite (Fe3O4) is of fundamental importance for Verwey transition near TV = 125 K, below which a complex lattice distortion and electron orders occur. Verwey transition is suppressed by chemical doping effects giving rise to well-documented first and second-order regimes, but the origin of the order change is unclea...

[Wonjin Jang, Min-Kyun Cho / Prof. Dohun Kim] Single-Shot Readout of a Driven Hybrid Qubit in a GaAs... Jun 15, 2021 l Hit 1993

We report a single-shot-based projective readout of a semiconductor hybrid qubit formed by three electrons in a GaAs double quantum dot. Voltage-controlled adiabatic transitions between the qubit operations and readout conditions allow high-fidelity mapping of quantum states. We show that a large ratio both in relaxati...