Highly Efficient Room-Temperature Spin-Orbit-Torque Switching in a Van der Waals Heterostructure of Topological Insulator and Ferromagnet.

All-Van der Waals (vdW)-material-based heterostructures with atomically sharp interfaces offer a versatile platform for high-performing spintronic functionalities at room temperature. One of the key components is vdW topological insulators (TIs), which can produce a strong spin-orbit-torque (SOT) through the spin-momentum locking of their topological surface state (TSS). However, the relatively low conductance of the TSS introduces a current leakage problem through the bulk states of the TI or the adjacent ferromagnetic metal layers, reducing the interfacial charge-to-spin conversion efficiency (qICS). Here, a vdW heterostructure is used consisting of atomically-thin layers of a bulk-insulating TI Sn-doped Bi1.1Sb0.9Te2S1 and a room-temperature ferromagnet Fe3GaTe2, to enhance the relative current ratio on the TSS up to ≈20%. The resulting qICS reaches ≈1.65 nm-1 and the critical current density Jc ≈0.9 × 106 Acm-2 at 300 K, surpassing the performance of TI-based and heavy-metal-based SOT devices. These findings demonstrate that an all-vdW heterostructure with thickness optimization offers a promising platform for efficient current-controlled magnetization switching at room temperature.

2023 Korean sexually transmitted infections treatment guidelines for Mycoplasma genitalium by KAUTII.

The Korean Association of Urogenital Tract Infection and Inflammation and the Korea Disease Control and Prevention Agency updated the Korean sexually transmitted infections (STIs) guidelines to respond to the changing epidemiologic trends, evolving scientific evidence, and advances in laboratory diagnostics and research. The main recommendations in the Mycoplasma genitalium infection parts of the Korean STIs guidelines 2023 revision are as follows: 1) For initial treatment: azithromycin 500 mg orally in a single dose, then 250 mg once daily for 4 days. 2) In case of treatment failure or recurrence, a macrolide susceptibility/resistance test is required, when susceptibility/resistance test is not feasible, doxycycline or minocycline 100 mg orally twice daily for 7 days, followed by azithromycin 1 g orally on the first day, then azithromycin 500 mg orally once daily for 3 days and then a test-of-cure should be considered 3 weeks after completion of therapy. 3) In case of macrolide sensitivity, doxycycline or minocycline 100 mg orally twice daily for 7 days, followed by azithromycin 1 g orally initial dose, then azithromycin 500 mg orally once daily for 3 days. 4) In case of macrolide resistance, doxycycline or minocycline 100 mg orally twice daily for 7 days, followed by moxifloxacin 400 mg orally once daily for 7 days. In the Korean STIs guideline 2023, macrolide resistance-guided antimicrobial therapy was emphasized due to the increased prevalence of macrolide resistance worldwide. Therefore, in case of treatment failure or recurrence, a macrolide susceptibility/resistance test is required.

Multiplexed DNA-functionalized graphene sensor with artificial intelligence-based discrimination performance for analyzing chemical vapor compositions.

This study presents a new technology that can detect and discriminate individual chemical vapors to determine the chemical vapor composition of mixed chemical composition in situ based on a multiplexed DNA-functionalized graphene (MDFG) nanoelectrode without the need to condense the original vapor or target dilution. To the best of our knowledge, our artificial intelligence (AI)-operated arrayed electrodes were capable of identifying the compositions of mixed chemical gases with a mixed ratio in the early stage. This innovative technology comprised an optimized combination of nanodeposited arrayed electrodes and artificial intelligence techniques with advanced sensing capabilities that could operate within biological limits, resulting in the verification of mixed vapor chemical components. Highly selective sensors that are tolerant to high humidity levels provide a target for "breath chemovapor fingerprinting" for the early diagnosis of diseases. The feature selection analysis achieved recognition rates of 99% and above under low-humidity conditions and 98% and above under humid conditions for mixed chemical compositions. The 1D convolutional neural network analysis performed better, discriminating the compositional state of chemical vapor under low- and high-humidity conditions almost perfectly. This study provides a basis for the use of a multiplexed DNA-functionalized graphene gas sensor array and artificial intelligence-based discrimination of chemical vapor compositions in breath analysis applications.

Robust Interlayer-Coherent Quantum Hall States in Twisted Bilayer Graphene.

We introduce a novel two-dimensional electronic system with ultrastrong interlayer interactions, namely, twisted bilayer graphene with a large twist angle, as an ideal ground for realizing interlayer-coherent excitonic condensates. In these systems, sub-nanometer atomic separation between the layers allows significant interlayer interactions, while interlayer electron tunneling is geometrically suppressed due to the large twist angle. By fully exploiting these two features we demonstrate that a sequence of odd-integer quantum Hall states with interlayer coherence appears at the second Landau level (N = 1). Notably the energy gaps for these states are of order 1 K, which is several orders of magnitude greater than those in GaAs. Furthermore, a variety of quantum Hall phase transitions are observed experimentally. All the experimental observations are largely consistent with our phenomenological model calculations. Hence, we establish that a large twist angle system is an excellent platform for high-temperature excitonic condensation.

mgpB genotyping and genetic diversity for antimicrobial resistance of Mycoplasma genitalium.

Introduction. Antimicrobial resistance (AMR) among Mycoplasma genitalium is a global issue. Understanding the transmission dynamics of infection is an important factor in reducing the occurrence of AMR.Hypothesis/Gap Statement. There is limited information on the genotyping and AMR traits of M. genitalium.Aims. Single-locus sequence-based (SLSB) mgpB sequence typing and genetic diversity analyses of AMR M. genitalium isolated from patients in the Republic of Korea were performed to clarify the transmission dynamics and eludicate proper management.Methodology. Sanger sequencing of mgpB, 23S rRNA, parC and gyrA genes from a total of 103 M. genitalium-positive specimens from 89 patients was carried out.Results. Twenty-seven different mgpB genotypes (GTs) were identified; 12 had been reported previously and 15 had not. GT7 and GT8 occurred frequently (n=38, 36.89 %, and n=16, 15.53 %, respectively). The genetic diversity of the AMR-determining sites was randomly dispersed among the different GTs. However, these GTs were classified into two phylogenetically distinct clusters that were significantly correlated with patient age and genetic diversity at positions 2058 and 2059 in the 23S rRNA gene. The GTs of 20 consecutive samples from 6 patients were compared to investigate temporal changes in GTs. One specimen changed its GT during follow-up, suggesting a new infection.Conclusions. mgpB sequence typing can be a reliable tool for epidemiological studies. Two clusters have different characteristics in terms of genetic diversity. The cluster with genetic diversity in the AMR-determining site may be explained by the high prevalence of the specimens and subsequent antimicrobial exposure during the study period.

Steady Floquet-Andreev states in graphene Josephson junctions.

Engineering quantum states through light-matter interaction has created a paradigm in condensed-matter physics. A representative example is the Floquet-Bloch state, which is generated by time-periodically driving the Bloch wavefunctions in crystals. Previous attempts to realize such states in condensed-matter systems have been limited by the transient nature of the Floquet states produced by optical pulses1-3, which masks the universal properties of non-equilibrium physics. Here we report the generation of steady Floquet-Andreev states in graphene Josephson junctions by continuous microwave application and direct measurement of their spectra by superconducting tunnelling spectroscopy. We present quantitative analysis of the spectral characteristics of the Floquet-Andreev states while varying the phase difference of the superconductors, the temperature, the microwave frequency and the power. The oscillations of the Floquet-Andreev-state spectrum with phase difference agreed with our theoretical calculations. Moreover, we confirmed the steady nature of the Floquet-Andreev states by establishing a sum rule of tunnelling conductance4, and analysed the spectral density of Floquet states depending on Floquet interaction strength. This study provides a basis for understanding and engineering non-equilibrium quantum states in nanodevices.

Spin-Orbit Torque Switching in an All-Van der Waals Heterostructure.

Current-induced control of magnetization in ferromagnets using spin-orbit torque (SOT) has drawn attention as a new mechanism for fast and energy efficient magnetic memory devices. Energy-efficient spintronic devices require a spin-current source with a large SOT efficiency (ξ) and electrical conductivity (σ), and an efficient spin injection across a transparent interface. Herein, single crystals of the van der Waals (vdW) topological semimetal WTe2  and vdW ferromagnet Fe3 GeTe2 are used to satisfy the requirements in their all-vdW-heterostructure with an atomically sharp interface. The results exhibit values of ξ ≈ 4.6 and σ ≈ 2.25 × 105  Ω-1 m-1 for WTe2 . Moreover, the significantly reduced switching current density of 3.90 × 106 A cm-2 at 150 K is obtained, which is an order of magnitude smaller than those of conventional heavy-metal/ferromagnet thin films. These findings highlight that engineering vdW-type topological materials and magnets offers a promising route to energy-efficient magnetization control in SOT-based spintronics.

Twisted van der Waals Josephson Junction Based on a High-Tc Superconductor.

Stacking two-dimensional van der Waals (vdW) materials rotated with respect to each other show versatility for studying exotic quantum phenomena. In particular, anisotropic layered materials have great potential for such twistronics applications, providing high tunability. Here, we report anisotropic superconducting order parameters in twisted Bi2Sr2CaCu2O8+x (Bi-2212) vdW junctions with an atomically clean vdW interface, achieved using the microcleave-and-stack technique. The vdW junctions with twist angles of 0° and 90° showed the maximum Josephson coupling, comparable to that of intrinsic Josephson junctions. As the twist angle approaches 45°, Josephson coupling is suppressed, and eventually disappears at 45°. The observed twist angle dependence of the Josephson coupling can be explained quantitatively by theoretical calculation with the d-wave superconducting order parameter of Bi-2212 and finite tunneling incoherence of the junction. Our results revealed the anisotropic nature of Bi-2212 and provided a novel fabrication technique for vdW-based twistronics platforms compatible with air-sensitive vdW materials.

Deep-ultraviolet electroluminescence and photocurrent generation in graphene/hBN/graphene heterostructures.

Hexagonal boron nitride (hBN) is a van der Waals semiconductor with a wide bandgap of ~ 5.96 eV. Despite the indirect bandgap characteristics of hBN, charge carriers excited by high energy electrons or photons efficiently emit luminescence at deep-ultraviolet (DUV) frequencies via strong electron-phonon interaction, suggesting potential DUV light emitting device applications. However, electroluminescence from hBN has not been demonstrated at DUV frequencies so far. In this study, we report DUV electroluminescence and photocurrent generation in graphene/hBN/graphene heterostructures at room temperature. Tunneling carrier injection from graphene electrodes into the band edges of hBN enables prominent electroluminescence at DUV frequencies. On the other hand, under DUV laser illumination and external bias voltage, graphene electrodes efficiently collect photo-excited carriers in hBN, which generates high photocurrent. Laser excitation micro-spectroscopy shows that the radiative recombination and photocarrier excitation processes in the heterostructures mainly originate from the pristine structure and the stacking faults in hBN. Our work provides a pathway toward efficient DUV light emitting and detection devices based on hBN.

Molecular mechanisms of macrolide and fluoroquinolone resistance among Korean isolates of Mycoplasma genitalium over a period of five years 2014-2019.

Antimicrobial resistance in Mycoplasma genitalium has become a global issue, and certain groups have a higher probability of acquiring resistant strains. Little is known about the genetic diversity and characteristics of the antimicrobial resistance-determining sites (ARDSs) of M. genitalium in the Korean population. Therefore, we examined the genetic diversity of the ARDSs of M. genitalium-positive urogenital samples obtained from Korean females (G1) and males (G2) visiting primary care clinics and DNA samples from referred males (G3) with persistent urethritis. From 2014 to 2019, 54 patients from G1, 86 patients from G2, and 68 patients from G3 were included in the study. Sanger sequencing was performed on the 2058/2059 sites in the 23S rRNA gene and quinolone resistance-determining regions (QRDRs) of M. genitalium. The rates of mutation in G1, G2, and G3 were 1.85, 5.81, and 48.53 %, respectively, for A2059G in the 23S rRNA gene (P<0.001); 1.85, 0, and 17.78 %, respectively, for M95R or I in gyrA (P<0.001); 0, 0, and 31.11 %, respectively, for D99N or G in gyrA (P<0.001); and 7.41, 16.28, and 30 %, respectively, for S83R or N or I in parC (P=0.015). A2059G significantly increased the risk of mutations at the gyrA95, gyrA99, and parC83 sites (all P<0.01). In conclusion, although the genetic diversity of the ARDSs of M. genitalium was variable among the groups, it was generally lower in isolates with macrolide resistance and higher in isolates with quinolone resistance in Korea compared with the isolates in other countries. The G3 group demonstrated increased genetic diversity at the A2059G, gyrA95, gyrA99, and parC83 sites.

Anisotropic Angstrom-Wide Conductive Channels in Black Phosphorus by Top-down Cu Intercalation.

Intercalation in black phosphorus (BP) can induce and modulate a variety of the properties including superconductivity like other two-dimensional (2D) materials. In this perspective, spatially controlled intercalation has the possibility to incorporate different properties into a single crystal of BP. We demonstrate anisotropic angstrom-wide (∼4.3 Å) Cu intercalation in BP, where Cu atoms are intercalated along a zigzag direction of BP because of its inherent anisotropy. With atomic structure, its microstructural effects, arising from the angstrom-wide Cu intercalation, were investigated and extended to relation with macrostructure. As the intercalation mechanism, it was revealed by in situ transmission electron microscopy and theoretical calculation that Cu atoms are intercalated through top-down direction of BP. The Cu intercalation anisotropically induces transition of angstrom-wide electronic channels from semiconductor to semimetal in BP. Our findings throw light on the fundamental relationship between microstructure changes and properties in intercalated BP, and tailoring anisotropic 2D materials at angstrom scale.

Josephson junction infrared single-photon detector.

Josephson junctions are superconducting devices used as high-sensitivity magnetometers and voltage amplifiers as well as the basis of high-performance cryogenic computers and superconducting quantum computers. Although device performance can be degraded by the generation of quasiparticles formed from broken Cooper pairs, this phenomenon also opens opportunities to sensitively detect electromagnetic radiation. We demonstrate single near-infrared photon detection by coupling photons to the localized surface plasmons of a graphene-based Josephson junction. Using the photon-induced switching statistics of the current-biased device, we reveal the critical role of quasiparticles generated by the absorbed photon in the detection mechanism. The photon sensitivity will enable a high-speed, low-power optical interconnect for future superconducting computing architectures.

Characterization and Trend of Co-Infection with Neisseria gonorrhoeae and Chlamydia trachomatis from the Korean National Infectious Diseases Surveillance Database.

PURPOSE: We analyzed the database from the Korean National Infectious Diseases Surveillance to reveal clinical characteristics of co-infection with Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT). MATERIALS AND METHODS: Eligible cases included a single NG infection (male/female) for 6,421 (4,975/1,446), a single CT infection for 20,436 (6,107/14,329), and co-infection for 498 (233/265) between 2011 and 2015. RESULTS: Cases of NG and CT have increased for 5 years; the proportion of co-infected male has increased continuously and was positively correlated with that of CT infections. But the proportion of co-infected female was positively correlated with that of NG infections, following an expanded wavelike-pattern. Generally, people with co-infection was younger than either infection alone (p=0.001). But the characteristics of co-infection revealed sex-specific differences. While the co-infected females were younger than females in NG (p=0.001) or CT group (p=0.001), the co-infected males were younger than males in CT (p=0.001) only, not males in the NG group (p=0.394). Amongst males, 4.47% with NG had CT infection, while in female 15.49% with NG had CT (p=0.001). In contrast, in male 3.68% with CT infection had NG infection and in female 1.82% of CT had NG (p=0.001). Young people in both sexes have increased risks of co-infection bi-directionally (all p=0.001), except males with NG that were also co-infected with CT (p=0.642). CONCLUSIONS: The sex-specific findings in co-infection may improve understanding of gender-specific characteristics in NG and CT infections. Co-infected people are increasing for 5 years. Therefore, we must consider long-term complication of the co-infected people.

Graphene-based Josephson junction microwave bolometer.

Sensitive microwave detectors are essential in radioastronomy1, dark-matter axion searches2 and superconducting quantum information science3,4. The conventional strategy to obtain higher-sensitivity bolometry is the nanofabrication of ever smaller devices to augment the thermal response5-7. However, it is difficult to obtain efficient photon coupling and to maintain the material properties in a device with a large surface-to-volume ratio owing to surface contamination. Here we present an ultimately thin bolometric sensor based on monolayer graphene. To utilize the minute electronic specific heat and thermal conductivity of graphene, we develop a superconductor-graphene-superconductor Josephson junction8-13 bolometer embedded in a microwave resonator with a resonance frequency of 7.9 gigahertz and over 99 per cent coupling efficiency. The dependence of the Josephson switching current on the operating temperature, charge density, input power and frequency shows a noise-equivalent power of 7 × 10-19 watts per square-root hertz, which corresponds to an energy resolution of a single 32-gigahertz photon14, reaching the fundamental limit imposed by intrinsic thermal fluctuations at 0.19 kelvin. Our results establish that two-dimensional materials could enable the development of bolometers with the highest sensitivity allowed by the laws of thermodynamics.

Author Correction: Evidence of higher-order topology in multilayer WTe2 from Josephson coupling through anisotropic hinge states.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Evidence of higher-order topology in multilayer WTe2 from Josephson coupling through anisotropic hinge states.

Td-WTe2 (non-centrosymmetric and orthorhombic), a type-II Weyl semimetal, is expected to have higher-order topological phases with topologically protected, helical one-dimensional hinge states when its Weyl points are annihilated. However, the detection of these hinge states is difficult due to the semimetallic behaviour of the bulk. In this study, we have spatially resolved the hinge states by analysing the magnetic field interference of the supercurrent in Nb-WTe2-Nb proximity Josephson junctions. The Josephson current along the a axis of the WTe2 crystal, but not along the b axis, showed a sharp enhancement at the edges of the junction, and the amount of enhanced Josephson current was comparable to the upper limits of a single one-dimensional helical channel. Our experimental observations suggest a higher-order topological phase in WTe2 and its corresponding anisotropic topological hinge states, in agreement with theoretical calculations. Our work paves the way for the study of hinge states in topological transition-metal dichalcogenides and analogous phases.

Electrically focus-tuneable ultrathin lens for high-resolution square subpixels.

Owing to the tremendous demands for high-resolution pixel-scale thin lenses in displays, we developed a graphene-based ultrathin square subpixel lens (USSL) capable of electrically tuneable focusing (ETF) with a performance competitive with that of a typical mechanical refractive lens. The fringe field due to a voltage bias in the graphene proves that our ETF-USSL can focus light onto a single point regardless of the wavelength of the visible light-by controlling the carriers at the Dirac point using radially patterned graphene layers, the focal length of the planar structure can be adjusted without changing the curvature or position of the lens. A high focusing efficiency of over 60% at a visible wavelength of 405 nm was achieved with a lens thickness of <13 nm, and a change of 19.42% in the focal length with a 9% increase in transmission was exhibited under a driving voltage. This design is first presented as an ETF-USSL that can be controlled in pixel units of flat panel displays for visible light. It can be easily applied as an add-on to high resolution, slim displays and provides a new direction for the application of multifunctional autostereoscopic displays.

Strain effect on magnetic-exchange-induced phonon splitting in NiO films.

NiO thin films with various strains were grown on SrTiO3 (STO) and MgO substrates using a pulsed laser deposition technique. The films were characterized using an x-ray diffraction, atomic force microscopy, and infrared reflectance spectroscopy. The films grown on STO (001) substrate show a compressive in-plane strain which increases as the film thickness is reduced resulting in an increase of the NiO phonon frequency. On the other hand, a tensile strain was detected in the NiO film grown on MgO (001) substrate which induces a softening of the phonon frequency. Overall, the variation of in-plane strain from -0.36% (compressive) to 0.48% (tensile) yields the decrease of the phonon frequency from 409.6 cm-1 to 377.5 cm-1 which occurs due to the ∼1% change of interatomic distances. The magnetic exchange-driven phonon splitting Δω in three different samples, with relaxed (i.e. zero) strain, 0.36% compressive strain and 0.48% tensile strain, was measured as a function of temperature. The Δω increases on cooling in NiO relaxed film as in the previously published work on a bulk crystal. The splitting increases on cooling also in 0.48% tensile strained film, but Δω is systematically 3-4 cm-1 smaller than in relaxed film. Since the phonon splitting is proportional to the non-dominant magnetic exchange interaction J 1, the reduction of phonon splitting in tensile-strained film was explained by a diminishing of J 1 with lattice expansion. Increase of Δω on cooling can be also explained by rising of J 1 with reduced temperature.