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In two-dimensional (2D) NbSe2 crystal, which lacks inversion symmetry, strong spin-orbit coupling aligns the spins of Cooper pairs to the orbital valleys, forming Ising Cooper pairs (ICPs). The unusual spin texture of ICPs can be further modulated by introducing magnetic exchange. Here, we report unconventional supercurrent phase in van der Waals heterostructure Josephson junctions (JJs) that couples NbSe2 ICPs across an atomically thin magnetic insulator (MI) Cr2Ge2Te6. By constructing a superconducting quantum interference device (SQUID), we measure the phase of the transferred Cooper pairs in the MI JJ. We demonstrate a doubly degenerate nontrivial JJ phase (ϕ), formed by momentum-conserving tunneling of ICPs across magnetic domains in the barrier. The doubly degenerate ground states in MI JJs provide a two-level quantum system that can be utilized as a new dissipationless component for superconducting quantum devices. Our work boosts the study of various superconducting states with spin-orbit coupling, opening up an avenue to designing new superconducting phase-controlled quantum electronic devices. Van der Waals structures provide a new platform to explore novel physics of superconductor/ferromagnet interfaces. Here, NbSe2 Josephson junction with Cr2Ge2Te6 enables non-trivial Josephson phase by spin-dependent interaction, boosting the study of superconducting states with spin-orbit coupling and phase-controlled quantum electronic device.

We use high-resolution angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations to study the electronic and magnetic properties of La2Ni7, an itinerant magnetic system with a series of three magnetic transition temperatures upon cooling, which end in a weak itinerant antiferromagnetic (wAFM) ground state. Our APRES data reveal several electron and hole pockets that have hexagonal symmetry near the $\Gamma$ point. We observe significant reconstruction of the band structure upon successive magnetic transitions at T1 = 61 K, T2 = 57 K and T3 = 42 K. The experimental data are in a reasonable agreement with DFT calculations, demonstrating their applicability to itinerant antiferromagnet systems. Our results detail the effects of magnetic ordering on the electronic structure in a Ni-based weak antiferromagnet., Comment: 17 pages, 4 figures

We studied the electronic structure of ${\mathrm{PtPb}}_{4}$ using laser angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations. This material is closely related to ${\mathrm{PtSn}}_{4}$, which exhibits exotic topological properties such as Dirac node arcs. The Fermi surface (FS) of ${\mathrm{PtPb}}_{4}$ consists of two electron pockets at the center of the Brillouin zone (BZ) and several hole pockets around the zone boundaries. Our ARPES data reveal significant Rashba splitting at the $\mathrm{\ensuremath{\Gamma}}$ point, in agreement with DFT calculations. The presence of Rashba splitting may render this material of potential interest for spintronic applications.

CeBi has an intricate magnetic phase diagram whose fully-polarized state has recently been suggested as a Weyl semimetal, though the role of $f$ states in promoting strong interactions has remained elusive. Here we focus on the less-studied, but also time-reversal symmetry-breaking ferrimagnetic phase of CeBi, where our density functional theory (DFT) calculations predict additional Weyl nodes near the Fermi level $E_\mathrm{F}$. We use spin-polarized scanning tunneling microscopy and spectroscopy to image the surface ferrimagnetic order on the itinerant Bi $p$ states, indicating their orbital hybridization with localized Ce $f$ states. We observe suppression of this spin-polarized signature at $E_\mathrm{F}$, coincident with a Fano line shape in the conductance spectra, suggesting the Bi $p$ states partially Kondo screen the $f$ magnetic moments, and this $p-f$ hybridization causes strong Fermi-level band renormalization. The $p$ band flattening is supported by our quasiparticle interference (QPI) measurements, which also show band splitting in agreement with DFT, painting a consistent picture of a strongly interacting magnetic Weyl semimetal.

Time reversal symmetric (TRS) invariant topological insulators (TIs) fullfil a paradigmatic role in the field of topological materials, standing at the origin of its development. Apart from TRS protected strong TIs, it was realized early on that more confounding weak topological insulators (WTI) exist. WTIs depend on translational symmetry and exhibit topological surface states only in certain directions making it significantly more difficult to match the experimental success of strong TIs. We here report on the discovery of a WTI state in RhBi2 that belongs to the optimal space group P\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar{1}$$\end{document}1¯, which is the only space group where symmetry indicated eigenvalues enumerate all possible invariants due to absence of additional constraining crystalline symmetries. Our ARPES, DFT calculations, and effective model reveal topological surface states with saddle points that are located in the vicinity of a Dirac point resulting in a van Hove singularity (VHS) along the (100) direction close to the Fermi energy (EF). Due to the combination of exotic features, this material offers great potential as a material platform for novel quantum effects., Weak topological insulators (WTI) remain difficult to be observed in experiments. Here, the authors discover a WTI state in RhBi2, where the topological surface states with saddle points result in a van Hove singularity along the (100) direction near Fermi energy.

Magnetic Weyl semimetals are expected to have extraordinary physical properties such as a chiral anomaly and large anomalous Hall effects that may be useful for future, potential, spintronics applications. However, in most known host materials, multiple pairs of Weyl points prevent a clear manifestation of the intrinsic topological effects. Our recent density functional theory (DFT) calculations study suggest that EuCd$_{2}$As$_{2}$ can host Dirac fermions in an antiferromagnetically (AFM) ordered state or a single pair of Weyl fermions in a ferromagnetically (FM) ordered state. Unfortunately, previously synthesized crystals ordered antiferromagnetically with $T_{\textrm{N}}$\,$\simeq$\,9.5\,K. Here, we report the successful synthesis of single crystals of EuCd$_{2}$As$_{2}$ that order ferromagnetically (FM) or antiferromagnetically (AFM) depending on the level of band filling, thus allowing for the use of magnetism to tune the topological properties within the same host. We explored their physical properties via magnetization, electrical transport, heat capacity, and angle resolved photoemission spectroscopy (ARPES) measurements and conclude that EuCd$_{2}$As$_{2}$ is an excellent, tunable, system for exploring the interplay of magnetic ordering and topology.

Low temperature ($\sim$ 20~K) electron irradiation with 2.5 MeV relativistic electrons was used to study the effect of controlled non-magnetic disorder on the normal and superconducting properties of the type-II Dirac semimetal PdTe$_2$. We report measurements of longitudinal and Hall resistivity, thermal conductivity and London penetration depth using tunnel-diode resonator technique for various irradiation doses. The normal state electrical resistivity follows Matthiessen rule with an increase of the residual resistivity at a rate of $\sim$0.77$ \mu \Omega$cm/$(\textrm{C}/\textrm{cm}^2)$. London penetration depth and thermal conductivity results show that the superconducting state remains fully gapped. The superconducting transition temperature is suppressed at a non-zero rate that is about sixteen times slower than described by the Abrikosov-Gor'kov dependence, applicable to magnetic impurity scattering in isotropic, single-band $s$-wave superconductors. To gain information about the gap structure and symmetry of the pairing state, we perform a detailed analysis of these experimental results based on insight from a generalized Anderson theorem for multi-band superconductors. This imposes quantitative constraints on the gap anisotropies for each of the possible pairing candidate states. We conclude that the most likely pairing candidate is an unconventional $A_{1g}^{+-}$ state. While we cannot exclude the conventional $A_{1g}^{++}$ and the triplet $A_{1u}$, we demonstrate that these states require additional assumptions about the orbital structure of the disorder potential to be consistent with our experimental results, e.g., a ratio of inter- to intra-band scattering for the singlet state significantly larger than one. Due to the generality of our theoretical framework, we think that it will also be useful for irradiation studies in other spin-orbit-coupled multi-orbital systems., Comment: 22 pages, 12 figures

Time reversal symmetric (TRS) invariant topological insulators (TIs) fullfil a paradigmatic role in the field of topological materials, standing at the origin of its development. Apart from TRS protected 'strong' TIs, it was realized early on that more confounding weak topological insulators (WTI) exist. WTIs depend on translational symmetry and exhibit topological surface states only in certain directions making it significantly more difficult to match the experimental success of strong TIs. We here report on the discovery of a WTI state in RhBi2 that belongs to the optimal space group P1, which is the only space group where symmetry indicated eigenvalues enumerate all possible invariants due to absence of additional constraining crystalline symmetries. Our ARPES, DFT calculations, and effective model reveal topological surface states with saddle points that are located in the vicinity of a Dirac point resulting in a van Hove singularity (VHS) along the (100) direction close to the Fermi energy. Due to the combination of exotic features, this material offers great potential as a material platform for novel quantum effects., Comment: 20 pages plus supplement

Strain describes the deformation of a material as a result of applied stress. It has been widely employed to probe transport properties of materials, ranging from semiconductors to correlated materials. In order to understand, and eventually control, transport behavior under strain, it is important to quantify the effects of strain on the electronic bandstructure, carrier density, and mobility. Here, we demonstrate that much information can be obtained by exploring magnetoelastoresistance (MER), which refers to magnetic field-driven changes of the elastoresistance. We use this powerful approach to study the combined effect of strain and magnetic fields on the semimetallic transition metal dichalcogenide [Formula: see text]. We discover that WTe(2) shows a large and temperature-nonmonotonic elastoresistance, driven by uniaxial stress, that can be tuned by magnetic field. Using first-principle and analytical low-energy model calculations, we provide a semiquantitative understanding of our experimental observations. We show that in [Formula: see text] , the strain-induced change of the carrier density dominates the observed elastoresistance. In addition, the change of the mobilities can be directly accessed by using MER. Our analysis also reveals the importance of a heavy-hole band near the Fermi level on the elastoresistance at intermediate temperatures. Systematic understanding of strain effects in single crystals of correlated materials is important for future applications, such as strain tuning of bulk phases and fabrication of devices controlled by strain.

Large crystals of Yb14MgSb11 were grown through a Sn flux method. Magnetic susceptibility measurements yield an effective magnetic moment of 3.4(1) μB, revealing the presence of both divalent and trivalent Yb in Yb14MgSb11. Previously assumed to only contain Yb2+ as in Yb14MnSb11, the mixed valency demonstrates that Yb14MgSb11 is a Zintl phase.

A Scanning Tunneling Microscope (STM) is one of the most important scanning probe tools available to study and manipulate matter at the nanoscale. In a STM, a tip is scanned on top of a surface with a separation of a few \AA. Often, the tunneling current between tip and sample is maintained constant by modifying the distance between the tip apex and the surface through a feedback mechanism acting on a piezoelectric transducer. This produces very detailed images of the electronic properties of the surface. The feedback mechanism is nearly always made using a digital processing circuit separate from the user computer. Here we discuss another approach, using a computer and data acquisition through the USB port. We find that it allows succesful ultra low noise studies of surfaces at cryogenic temperatures. We show results on different compounds, a type II Weyl semimetal (WTe$_2$), a quasi two-dimensional dichalcogenide superconductor (2H-NbSe$_2$), a magnetic Weyl semimetal (Co$_3$Sn$_2$S$_2$) and an iron pnictide superconductor (FeSe)., Comment: Instrumentation paper

Materials with the ideal case of a single pair of Weyl points (WPs) are highly desirable for elucidating the unique properties of Weyl fermions. $\mathrm{EuC}{\mathrm{d}}_{2}\mathrm{A}{\mathrm{s}}_{2}$ is an antiferromagnetic topological insulator or Dirac semimetal depending on the different magnetic configurations. Using first-principles band-structure calculations, we show that inducing ferromagnetism in $\mathrm{EuC}{\mathrm{d}}_{2}\mathrm{A}{\mathrm{s}}_{2}$ can generate a single pair of WPs from splitting the single pair of antiferromagnetic Dirac points due to its half-metallic nature. Analysis with a low-energy effective Hamiltonian shows that a single pair of WPs is obtained in $\mathrm{EuC}{\mathrm{d}}_{2}\mathrm{A}{\mathrm{s}}_{2}$ because the Dirac points are very close to the zone center and the ferromagnetic exchange splitting is large enough to push one pair of WPs to merge and annihilate at \ensuremath{\Gamma} while the other pair survives. Furthermore, we predict that alloying with Ba at the Eu site can stabilize the ferromagnetic configuration and generate a single pair of Weyl points without application of a magnetic field.

We use tunable, vacuum ultraviolet laser-based angle-resolved photoemission spectroscopy and density functional theory calculations to study the electronic properties of Dirac semimetal candidate cubic PtBi${}_{2}$. In addition to bulk electronic states we also find surface states in PtBi${}_{2}$ which is expected as PtBi${}_{2}$ was theoretical predicated to be a candidate Dirac semimetal. The surface states are also well reproduced from DFT band calculations. Interestingly, the topological surface states form Fermi contours rather than double Fermi arcs that were observed in Na$_3$Bi. The surface bands forming the Fermi contours merge with bulk bands in proximity of the Dirac points projections, as expected. Our data confirms existence of Dirac states in PtBi${}_{2}$ and reveals the fragility of the Fermi arcs in Dirac semimetals. Because the Fermi arcs are not topologically protected in general, they can be deformed into Fermi contours, as proposed by [Kargarian {\it et al.}, PNAS \textbf{113}, 8648 (2016)]. Our results demonstrate validity of this theory in PtBi${}_{2}$., Comment: 6 pages, 4 figures

To determine the tumor immune cell landscape after transcatheter arterial bland embolization (TAE) in a clinically relevant rat hepatocellular carcinoma (HCC) model.Buffalo rats (n = 21) bearing syngeneic McArdle RH-7777 rat hepatoma cells implanted into the left hepatic lobe underwent TAE using 70-150 µm beads (n = 9) or hepatic artery saline infusion (n = 12). HCC nodules, peritumoral margin, adjacent non-cancerous liver, and splenic parenchyma were collected and disaggregated to generate single-cell suspensions for immunological characterization 14 d after treatment. Changes in tumor-infiltrating immune subsets including CD4 T cells (Th17 and Treg), CD8 cytotoxic T cells (IFNγ), and neutrophils were evaluated by multiparameter flow cytometry. Migration and colony formation assays were performed to examine the effect of IL-17, a signature cytokine of Th17 cells, on McArdle RH-7777 hepatoma cells under conditions simulating post-embolization environment (i.e., hypoxia and nutrient privation). Statistical significance was determined by the Student unpaired t test or one-way ANOVA.TAE induces increased infiltration of Th17 cells in liver tumors when compared with controls 14 d after treatment (0.29 ± 0.01 vs. 0.19 ± 0.02; p = 0.02). A similar pattern was observed in the spleen (1.41 ± 0.13 vs. 0.57 ± 0.08; p 0.001), indicating both local and systemic effect. No significant differences in the percentage of FoxP3 + Tregs, IFNγ-producing CD4 T cells, and CD8 T cells were observed between groups (p 0.05). In vitro post-embolization assays demonstrated that IL-17 reduces McA-RH7777 cell migration at 24-48 h (p = 0.003 and p = 0.002, respectively).Transcatheter hepatic arterial bland embolization induces local and systemic increased infiltration of Th17 cells and expression of their signature cytokine IL-17. In a simulated post-embolization environment, IL-17 significantly reduced McA-RH7777 cell migration.

A striking feature of time-reversal symmetry (TRS) protected topological insulators (TIs) is that they are characterized by a half integer quantum Hall effect on the boundary when the surface states are gapped by time-reversal breaking perturbations. While TRS-protected TIs have become increasingly under control, magnetic analogs are still a largely unexplored territory with novel rich structures. In particular, magnetic topological insulators can also host a quantized axion term in the presence of lattice symmetries. Since these symmetries are naturally broken on the boundary, the surface states can develop a gap without external manipulation. In this paper, we combine theoretical analysis, density-functional calculations and experimental evidence to reveal intrinsic axion insulating behavior in ${\mathrm{MnBi}}_{6}{\mathrm{Te}}_{10}$. The quantized axion term arises from the simplest possible mechanism in the antiferromagnetic regime where it is protected by inversion symmetry and the product of a fractional translation and TRS. The anticipated gapping of the Dirac surface state at the edge is subsequently experimentally established using angle resolved photoemission spectroscopy (ARPES). As a result, this system provides the magnetic analog of the simplest TRS-protected TI with a single, gapped Dirac cone at the surface.

Bi2Te3 is a well-known thermoelectric material and, as a new form of quantum matter, a topological insulator. Variation of local chemical composition in Bi2Te3 results in formation of several types of atomic defects, including Bi and Te vacancies and Bi and Te antisite defects; these defects can strongly affect material functionality via generation of free electrons and/or holes. Nonuniform distribution of atomic defects produces electronic inhomogeneity, which can be detected by 125Te nuclear magnetic resonance (NMR). Here we report on 125Te NMR and Seebeck effect (heat to electrical energy conversion) for two single crystalline samples: (#1) grown from stoichiometric composition by Bridgman technique and (#2) grown out of Te-rich, high temperature flux. The Seebeck coefficients of these samples show p- and n-type conductivity, respectively, arising from different atomic defects. 125Te NMR spectra and spin–lattice relaxation measurements demonstrate that both Bi2Te3 samples are electronically inhomogeneo...

Large crystals of Yb14MgSb11 were grown through a Sn flux method. Magnetic susceptibility measurements yield an effective magnetic moment of 3.4(1) μB, revealing the presence of both divalent and trivalent Yb in Yb14MgSb11. Previously assumed to only contain Yb2+ as in Yb14MnSb11, the mixed valency demonstrates that Yb14MgSb11 is a Zintl phase.

The microscopic details of the suppression of antiferromagnetic order in the Kondo-lattice series Ce$_{1-x}$La$_{x}$Cu$_{2}$Ge$_{2}$ due to nonmagnetic dilution by La are revealed through neutron diffraction results for $x=0.20$, $0.40$, $0.75$, and $0.85$. Magnetic Bragg peaks are found for $0.20\le x\le0.75$, and both the N\'{e}el temperature, $T_{\textrm{N}}$, and the ordered magnetic moment per Ce, $\mu$, linearly decrease with increasing $x$. The reduction in $\mu$ points to strong hybridization of the increasingly diluted Ce $4f$ electrons, and we find a remarkable quadratic dependence of $\mu$ on the Kondo-coherence temperature. We discuss our results in terms of local-moment- versus itinerant-type magnetism and mean-field theory, and show that Ce$_{1-x}$La$_{x}$Cu$_{2}$Ge$_{2}$ provides an exceptional opportunity to quantitatively study competing magnetic interactions in a Kondo lattice.

The recently discovered material PtSn$_4$ is known to exhibit extremely large magnetoresistance (XMR) that also manifests Dirac arc nodes on the surface. PdSn$_4$ is isostructure to PtSn$_4$ with same electron count. We report on the physical properties of high quality single crystals of PdSn$_4$ including specific heat, temperature and magnetic field dependent resistivity and magnetization, and electronic band structure properties obtained from angle resolved photoemission spectroscopy (ARPES). We observe that PdSn$_4$ has physical properties that are qualitatively similar to those of PtSn$_4$, but find also pronounced differences. Importantly, the Dirac arc node surface state of PtSn$_4$ is gapped out for PdSn$_4$. By comparing these similar compounds, we address the origin of the extremely large magnetoresistance in PdSn$_4$ and PtSn$_4$; based on detailed analysis of the magnetoresistivity, $\rho(H,T)$, we conclude that neither carrier compensation nor the Dirac arc node surface state are primary reason for the extremely large magnetoresistance. On the other hand, we find that surprisingly Kohler's rule scaling of the mangnetoresistance, which describes a self-similarity of the field induced orbital electronic motion across different length scales and is derived for a simple electronic response of metals to applied in a magnetic field is obeyed over the full range of temperatures and field strengths that we explore.

We present measurements of superconducting transition temperature, resistivity, magnetoresistivity, and temperature dependence of the upper critical field of ${\mathrm{Ta}}_{4}{\mathrm{Pd}}_{3}{\mathrm{Te}}_{16}$ under pressures up to 16.4 kbar. All measured properties have an anomaly at $\ensuremath{\sim}2--4$ kbar pressure range; in particular there is a maximum in ${T}_{c}$ and upper critical field, ${H}_{c2}(0)$, and minimum in low temperature, normal state resistivity. Qualitatively, the data can be explained considering the density of state at the Fermi level as a dominant parameter.

Given the importance of crystal symmetry for the emergence of topological quantum states, we have studied, as exemplified in $\mathrm{NbNiT}{\mathrm{e}}_{2}$, the interplay of crystal symmetry, atomic displacements (lattice vibration), band degeneracy, and band topology. For the $\mathrm{NbNiT}{\mathrm{e}}_{2}$ structure in space-group 53 (Pmna)---having an inversion center arising from two glide planes and one mirror plane with a twofold rotation and screw axis---a full gap opening exists between two band manifolds near the Fermi energy. Upon atomic displacements by optical phonons, the symmetry lowers to space-group $28(Pma2)$, eliminating one glide plane along $c$, the associated rotation and screw axis, and the inversion center. As a result, 20 Weyl points emerge, including four type-II Weyl points in the \ensuremath{\Gamma}-$X$ direction at the boundary between a pair of adjacent electron and hole bands. Thus, optical phonons may offer control of the transition to a Weyl fermion state.

We use temperature- and field-dependent resistivity measurements [Shubnikov--de Haas (SdH) quantum oscillations] and ultrahigh resolution, tunable, vacuum ultraviolet (VUV) laser-based angle-resolved photoemission spectroscopy (ARPES) to study the three-dimensionality (3D) of the bulk electronic structure in WTe2, a type-II Weyl semimetal. The bulk Fermi surface (FS) consists of two pairs of electron pockets and two pairs of hole pockets along the X-Gamma-X direction as detected by using an incident photon energy of 6.7 eV, which is consistent with the previously reported data. However, if using an incident photon energy of 6.36 eV, another pair of tiny electron pockets is detected on both sides of the Gamma point, which is in agreement with the small quantum oscillation frequency peak observed in the magnetoresistance. Therefore, the bulk, 3D FS consists of three pairs of electron pockets and two pairs of hole pockets in total. With the ability of fine tuning the incident photon energy, we demonstrate the strong three-dimensionality of the bulk electronic structure in WTe2. The combination of resistivity and ARPES measurements reveal the complete, and consistent, picture of the bulk electronic structure of this material., 6 pages, 3 figures

57 Fe Mossbauer spectroscopy measurements were performed on a powdered CuFe 2 Ge 2 sample that orders antiferromagnetically at ∼ 175 K. Whereas a paramagnetic doublet was observed above the Neel temperature, a superposition of paramagnetic doublet and magnetic sextet (in approximately 0.5:0.5 ratio) was observed in the magnetically ordered state, suggesting a magnetic structure similar to a double- Q spin density wave with half of the Fe paramagnetic and another half bearing static moment of ∼ 0.5 - 1 μ B . These results call for a re-evaluation of the recent neutron scattering data and band structure calculations, as well as for deeper examination of details of sample preparation techniques.

We report the growth, structure and characterization of BaZnGa, identifying it as the sole known ternary compound in the Ba-Zn-Ga system. Single crystals of BaZnGa can be grown out of excess Ba-Zn and adopt a tI36 structure type. There are three unique Ba sites and three M\,=\,Zn/Ga sites. Using DFT calculations we can argue that whereas one of these three M sites is probably solely occupied by Ga, the other two M sites, most likely, have mixed Zn/Ga occupancy. Temperature dependent resistivity and magnetization measurements suggest that BaZnGa is a poor metal with no electronic or magnetic phase transitions between 2\,K and 300\,K.

We have designed, constructed, and tested a unique cold finger suitable for angle resolved photoemission spectroscopy. This design is based on in situ helium reliquification and utilizes pulse tube cryocooler. The pulse tube can be removed for baking without breaking Ultra High Vacuum (UHV). This design also allows the use of non-UHV heater that can be replaced without the need to vent the system. The cold finger has minimal vibration, operates over a temperature range of 1.7 K-400 K, and has no measurable residual magnetization. In continuous mode, it can maintain a sample temperature of 2.6 K, while in single shot mode (by pumping on liquid helium), it can reach temperatures down to 1.8 K for a period of several hours.

목적: 캄필로박터 장염은 박테리아 장염의 흔한 원인 중 하나로 알려져 있다. 그러나 국내에서 소아에서의 캄필로박터 장염의 빈도와 임상 양상에 대한 연구는 드물다. 본 연구는 단일 병원 소아청소년과 환자에서 경험한 캄필로박터 장염의 빈도와 임상적 특징을 파악하고자 시행하였다. 방법: 2012년 1월부터 2017년 12월까지 을지대학교 을지병원 소아청소년과에 급성 위장관염으로 방문한 18세 이하 소아 환자로부터 대변 검체를 확보하였다. 그 중에서 배양 혹은 polymerase chain reaction을 통해 캄필로박터 장염으로 진단된 환자들의 의무기록을 후향적으로 검토하였다. 결과: 총 123명의 환자가 캄필로박터 장염을 진단받았으며 환자의 나이 중앙값은 12 세(사분위수, 8-16세)이었다. 캄필로박터 장염은 일년 내내 발생했지만 주로 6월과 9월 사이에 86명(69.9%)으로 집중적으로 발생하였다. 증상은 설사(97.6%), 발열(96.7%), 복통(94.3%), 구토(37.4%)와 두통(34.1%) 순으로 발생하였다. 복부 컴퓨터 단층 촬영은 25.2%의 사례에서 시행되었다. 다른 치료군과 비교했을 때, azithromycin 3일 요법으로 치료하는 것이 더 짧은 입원 기간과 관련이 있었다 (P

Systematic measurements of temperature-dependent magnetization, resistivity, and angle-resolved photoemission spectroscopy (ARPES) at ambient pressure as well as resistivity under pressures up to 5.25 GPa were conducted on single crystals of ${\mathrm{CrAuTe}}_{4}$. Magnetization data suggest that magnetic moments are aligned antiferromagnetically along the crystallographic $c$ axis below ${T}_{\mathrm{N}}=255$ K. ARPES measurements show band reconstruction due to the magnetic ordering. Magnetoresistance data show clear anisotropy, and, at high fields, quantum oscillations. The N\'eel temperature decreases monotonically under pressure, decreasing to ${T}_{\mathrm{N}}=236$ K at 5.22 GPa. The pressure dependencies of (i) ${T}_{\mathrm{N}}$, (ii) the residual resistivity ratio, and (iii) the size and power-law behavior of the low-temperature magnetoresistance all show anomalies near 2 GPa suggesting that there may be a phase transition (structural, magnetic, and/or electronic) induced by pressure. For pressures higher than 2 GPa a significantly different quantum oscillation frequency emerges, consistent with a pressure induced change in the electronic states.

Single crystalline, single phase CaKFe$_{4}$As$_{4}$ has been grown out of a high temperature, quaternary melt. Temperature dependent measurements of x-ray diffraction, anisotropic electrical resistivity, elastoresistivity, thermoelectric power, Hall effect, magnetization and specific heat, combined with field dependent measurements of electrical resistivity and field and pressure dependent measurements of magnetization indicate that CaKFe$_{4}$As$_{4}$ is an ordered, stoichiometric, Fe-based superconductor with a superconducting critical temperature, $T_c$ = 35.0 $\pm$ 0.2 K. Other than superconductivity, there is no indication of any other phase transition for 1.8 K $\leq T \leq$ 300 K. All of these thermodynamic and transport data reveal striking similarities to that found for optimally- or slightly over-doped (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$, suggesting that stoichiometric CaKFe$_4$As$_4$ is intrinsically close to what is referred to as "optimal-doped" on a generalized, Fe-based superconductor, phase diagram. The anisotropic superconducting upper critical field, $H_{c\text{2}}(T)$, of CaKFe$_{4}$As$_{4}$ was determined up to 630 kOe. The anisotropy parameter $\gamma(T)=H_{c\text{2}}^{\perp}/H_{c\text{2}}^{\|}$, for $H$ applied perpendicular and parallel to the c-axis, decreases from $\simeq 2.5$ at $T_c$ to $\simeq 1.5$ at 25 K which can be explained by interplay of paramagnetic pairbreaking and orbital effects. The slopes of $dH_{c\text{2}}^{\|}/dT\simeq-44$ kOe/K and $dH_{c\text{2}}^{\perp}/dT \simeq-109$ kOe/K at $T_c$ yield an electron mass anisotropy of $m_{\perp}/m_{\|}\simeq 1/6$ and short Ginzburg-Landau coherence lengths $\xi_{\|}(0)\simeq 5.8 \text{\AA}$ and $\xi_{\perp}(0)\simeq 14.3 \text{\AA}$. The value of $H_{c\text{2}}^{\perp}(0)$ can be extrapolated to $\simeq 920$ kOe, well above the BCS paramagnetic limit., Comment: 13 pages, 15 figures, part of arXiv:1606.02241 is included

We use ultrahigh resolution, tunable, vacuum ultraviolet laser angle-resolved photoemission spectroscopy (ARPES) to study the electronic properties of WTe$_2$, a material that was predicted to be a type-II Weyl semimetal. The Weyl fermion states in WTe2 were proposed to emerge at the crossing points of electron and hole pockets; and Fermi arcs connecting electron and hole pockets would be visible in the spectral function on (001) surface. Here we report the observation of such Fermi arcs in WTe2 confirming the theoretical predictions. This provides strong evidence for type-II Weyl semimetallic states in WTe2., Comment: 5 pages, 4 figures

We use ultra-high resolution, tunable, VUV laser-based, angle-resolved photoemission spectroscopy (ARPES) and temperature and field dependent resistivity and thermoelectric power (TEP) measurements to study the electronic properties of WTe2, a compound that manifests exceptionally large, temperature dependent magnetoresistance. The temperature dependence of the TEP shows a change of slope at T=175 K and the Kohler rule breaks down above 70-140 K range. The Fermi surface consists of two electron pockets and two pairs of hole pockets along the X-Gamma-X direction. Upon increase of temperature from 40K, the hole pockets gradually sink below the chemical potential. Like BaFe2As2, WTe2 has clear and substantial changes in its Fermi surface driven by modest changes in temperature. In WTe2, this leads to a rare example of temperature induced Lifshitz transition, associated with the complete disappearance of the hole pockets. These dramatic changes of the electronic structure naturally explain unusual features of the transport data., Comment: 5 pages, 3 figures

Solution growth of single crystals from high temperature solutions often involves the separation of residual solution from the grown crystals. For many growths of intermetallic compounds, this separation has historically been achieved with the use of plugs of silica wool. Whereas this is generally efficient in a mechanical sense, it leads to a significant contamination of the decanted liquid with silica fibers. In this paper we present a simple design for frit-disc alumina crucible sets that has made their use in the growth single crystals from high temperature solutions both simple and affordable. An alumina frit-disc allows for the clean separation of the residual liquid from the solid phase. This allows for the reuse of the decanted liquid, either for further growth of the same phase, or for subsequent growth of other, related phases. In this paper we provide examples of the growth of isotopically substituted TbCd$_{6}$ and icosahedral i-$R$Cd quasicrystals, as well as the separation of (i) the closely related Bi$_{2}$Rh$_{3}$S$_{2}$ and Bi$_{2}$Rh$_{3.5}$S$_{2}$ phases and (ii) PrZn$_{11}$ and Pr$_{2}$Zn$_{17}$., Comment: submitted to Philosophical Magazine

In Fe-doped Bi2Te3, we have observed higher mobility, larger linear magnetoresistance, and anomalous quantum oscillations. The angle dependence of Shubnikov-de Haas (SdH) oscillations gives two different periodicities depending on the angle from the c-axis. The low-angle SdH period is identified with a surface origin, while the high-angle period is against the surface origin. The high-angle SdH period well agrees with the de Haas-van Alphen (dHvA) period with a bulk origin. The physical parameters obtained from the quantum oscillations support the crossover between two-dimensional surface state and three-dimensional bulk phase by Fe doping in Bi2Te3.

Bi2Te3 is a well-known thermoelectric material for room-temperature operations because it has a high Seebeck coefficient, and the charge carrier type is easily tunable. However, the carrier type of Bi2Se3 is not tunable, which is one of the weaknesses for the thermoelectric applications, in spite of its high Seebeck coefficient. Here, we report the tuning of charge carriers in Bi2Te3 from n type to p type by doping Mn into the Bi sites. The carrier type is n type up to the Mn doping level of 5% and changes to p type above 5% Mn doping. The temperature-dependent resistivity of Bi2−xMnxSe3 shows a metallic behavior for x

We report a new class of three-dimensional topological insulators of transition metal doped Bi2Se3, TrxBi2Se3, and Bi2-xTrxSe3 (Tr = Cr, Fe, Cu) with x = 0.15, for the intercalation and substitution cases. With varying the doping atoms, a great variety of properties are observed in a single crystal form. The Cu-intercalated crystal shows superconducting behavior below 3 K, where the diamagnetic signal is found. The increase of carrier density at low temperature is likely to be responsible for the superconductivity. The magnetically doped case of the Fe-substituted Bi2Se3 exhibits dominance of ferromagnetic interactions, whereas the Cr-substituted Bi2Se3 favors antiferromagnetic interactions. From these results, we learn that the peculiar transport and magnetic properties of topological insulator Bi2Se3 are easily tunable by chemical doping elements, which change the Fermi energy and manipulate the charge carriers.