Search

Korea has been establishing international investment treaties through free trade agreements and bilateral or multilateral investment treaties. However, the legal doctrines on which these treaties are arguably incompatible with domestic law or national interests. Furthermore, critical commentators contend that these treaties are channels through which global standards are grafted into Korea’s domestic legal system. Nevertheless, this paper demonstrates that domestic legal elements or national interests are reflected in the international investment agreements, although this could be like passing a camel through the eye of a needle. Investment policy-makers usually tend to comply with international standards concerning investment protection schemes. However, the preceduralised treaty-making allows channels through which various perspectives can influence the treaty-making led by a particular department, from discussing trade policies to the legislative consent. Of course, this domestic influence cannot change the fundamental principle of international investment law. However, the national influence can have a small but not negligible impact on the flow of international investment law, which could ultimately contribute to secure a balance between investment protection and legitimate regulatory powers in the longer term.

We performed in-situ angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES (SARPES) experiments to investigate the relationship between electronic band structures and ferromagnetism in SrRuO$_3$ (SRO) thin films. Our high-quality ARPES and SARPES results show clear spin-lifted band structures. The spin polarization is strongly dependent on momentum around the Fermi level, whereas it becomes less dependent at high-binding energies. This experimental observation matches our dynamical mean-field theory (DMFT) results very well. As temperature increases from low to the Curie temperature, spin-splitting gap decreases and band dispersions become incoherent. Based on the ARPES study and theoretical calculation results, we found that SRO possesses spin-dependent electron correlations in which majority and minority spins are localized and itinerant, respectively. Our finding explains how ferromagnetism and electronic structure are connected, which has been under debate for decades in SRO., 6 pages, 4 figures

In spectroscopic experiments, data acquisition in multi-dimensional phase space may require long acquisition time, owing to the large phase space volume to be covered. In such case, the limited time available for data acquisition can be a serious constraint for experiments in which multidimensional spectral data are acquired. Here, taking angle-resolved photoemission spectroscopy (ARPES) as an example, we demonstrate a denoising method that utilizes deep learning as an intelligent way to overcome the constraint. With readily available ARPES data and random generation of training data set, we successfully trained the denoising neural network without overfitting. The denoising neural network can remove the noise in the data while preserving its intrinsic information. We show that the denoising neural network allows us to perform similar level of second-derivative and line shape analysis on data taken with two orders of magnitude less acquisition time. The importance of our method lies in its applicability to any multidimensional spectral data that are susceptible to statistical noise., Comment: 8 pages, 8 figures

The heavy fermion state with Kondo-hybridization (KH), usually manifested in f-electron systems with lanthanide or actinide elements, was recently discovered in several 3d transition metal compounds without f-electrons. However, KH has not yet been observed in 4d/5d transition metal compounds, since more extended 4d/5d orbitals do not usually form flat bands that supply localized electrons appropriate for Kondo pairing. Here, we report a doping- and temperature-dependent angle-resolved photoemission study on 4d Ca2-xSrxRuO4, which shows the signature of KH. We observed a spectral weight transfer in the γ-band, reminiscent of an orbital-selective Mott phase (OSMP). The Mott localized γ-band induces the KH with an itinerant β-band, resulting in spectral weight suppression around the Fermi level. Our work is the first to demonstrate the evolution of the OSMP with possible KH among 4d electrons, and thereby expands the material boundary of Kondo physics to 4d multi-orbital systems.

We present a strain-dependent time-resolved reflectometry experiment on $\mathrm{Ba}{({\mathrm{Fe}}_{0.955}{\mathrm{Co}}_{0.045})}_{2}{\mathrm{As}}_{2}$ in the nematic state. Uniaxial external pressure has usually been applied to obtain a single nematic domain. However, reflectivity with and without pumping under uniaxial strain along ${[110]}_{\text{tetr}}$ reveals an unexpected nematicity of which ${C}_{4}$ symmetry-breaking orientation is rotated by ${20}^{\ensuremath{\circ}}$. Our observation suggests a microscopic coexistence of ${B}_{2g}$ and ${B}_{1g}$ nematicity under uniaxial strain and possibly of an $XY$-type nematic order in the electron-doped iron pnictide.

Magnetism and spin–orbit coupling are two quintessential ingredients underlying topological transport phenomena in itinerant ferromagnets. When spin-polarized bands support nodal points/lines with band degeneracy that can be lifted by spin–orbit coupling, the nodal structures become a source of Berry curvature, leading to a large anomalous Hall effect. However, two-dimensional systems can possess stable nodal structures only when proper crystalline symmetry exists. Here we show that two-dimensional spin-polarized band structures of perovskite oxides generally support symmetry-protected nodal lines and points that govern both the sign and the magnitude of the anomalous Hall effect. To demonstrate this, we performed angle-resolved photoemission studies of ultrathin films of SrRuO3, a representative metallic ferromagnet with spin–orbit coupling. We show that the sign-changing anomalous Hall effect upon variation in the film thickness, magnetization and chemical potential can be well explained by theoretical models. Our work may facilitate new switchable devices based on ferromagnetic ultrathin films. The topological nature of the electronic structure of two-dimensional ferromagnetic SrRuO3 and its relationship to the anomalous Hall effect is explored through transport measurements, angle-resolved photoemission spectroscopy and theoretical modelling.

Diamagnetic flux is measured accurately in the Versatile Experiment Spherical Torus by simply measuring the change in the toroidal field (TF) coil current without additional poloidal loops. Stray couplings mainly with the plasma current (since poloidal field coils are aligned well to the TF coils) are compensated for, resulting in the minimum measurable flux of ±0.2 mWb determined mainly by the finite sensitivity of the TF coil current sensor, implying that the accuracy of this simple method can be improved by measuring the TF coil current change with a higher sensitivity. The poloidal beta is derived from the measured diamagnetic flux with the consideration of the low aspect ratio geometry. The poloidal beta and the plasma stored energy derived from the measurement are in good agreement with those from the equilibrium reconstruction, and the energy confinement time derived from the measurement is consistent with the L mode scaling.

A computationally efficient memory mapping predistorter is proposed to compensate for nonlinear distortion with memory induced by a combination of a linear pulse shaping filter and a travelling wave tube amplifier in orthogonal frequency division multiplexing (OFDM) systems. The proposed scheme utilizes a look up table (LUT) to store a small number of pre-calculated input-output relationships of the predistorter based on the fixed point iteration (FPI) we have presented in other study, and a simple memory mapping is employed for the data during actual system operation. We have implemented a 16-QAM, 256-subcarrier baseband OFDM modem and the proposed predistorter on a Texas Instruments' TMS320C30 digital signal processor, and experimental results show that the proposed predistorter achieves a very close performance of that based on the FPI even with a small LUT, while drastically reducing the computational complexity.

2-Aminopurine (2AP) absorption and fluorescence excitation and emission spectra in a series of solvents have been measured to assess effects of solvent polarity. Emission spectra of the free base shift to the red in solvents of a higher dielectric constant, including water but excepting dioxane. Excitation spectra also red-shift, except in water. A change in dipole moment of 2.8 D upon excitation is obtained from a Bilot-Kawski plot which includes data from potentially anomolous solvents such as alcohols but which excludes dioxane and aqueous solvents. Attachment of ribose or 2′-deoxyribose causes 1 to 2-nm shifts in the position of fluorescence excitation and emission spectra of 2AP in water and little change in fluorescence yield. Melting of the DNA duplex d[CTGA(2AP)TTCAG]2 yields a blue shift of the excitation and no shift of the emission spectrum-results consistent with increased exposure to water and formation of 2AP-water H bonds in the ground state. The spectral shift occurs 5°C or more below the helix melting temperature, implying a premelting structural change in the decamer.

Recently, a new contactless Jc measurement technique by monitoring nonlinear responses from a coil mounted in the proximity of a superconducting film was reported by Classen et al. [Rev. Sci. Instrum. 62, 996 (1991)]. An improved method to measure the nonlinear inductive response is developed using an inductance bridge circuit, which discriminates the third‐harmonic signal due to the nonlinearity from those of other origins. Moreover, in this technique, the phase of the third‐harmonic signal can be used to determine the critical current.