Spontaneous Atomic-Scale Polar Skyrmions and Merons on a SrTiO (001) Surface: Defect Engineering for Emerging Topological Orders.

The emergence of nontrivial topological order in condensed matter has been attracting a great deal of attention owing to its promising technological applications in novel functional nanodevices. In ferroelectrics, the realization of polar topological order at an ultimately small scale is extremely challenging due to the lack of chiral interaction and the critical size of the ferroelectricity. Here, we break through these limitations and demonstrate that the ultimate atomic-scale polar skyrmion and meron (∼2 nm) can be induced by engineering oxygen vacancies on the SrTiO (001) surface based on first-principles calculations.

Electronic strengthening mechanism of covalent Si via excess electron/hole doping.

Brittle fracture of a covalent material is ultimately governed by the strength of the electronic bonds. Recently, attempts have been made to alter the mechanical properties including fracture strength by excess electron/hole doping. However, the underlying mechanics/mechanism of how these doped electrons/holes interact with the bond and changes its strength is yet to be revealed.

Large anomalous Nernst effect and nodal plane in an iron-based kagome ferromagnet.

Anomalous Nernst effect (ANE), converting a heat flow to transverse electric voltage, originates from the Berry phase of electronic wave function near the Fermi energy . Thus, the ANE provides a sensitive probe to detect a topological state that produces large Berry curvature. In addition, a magnet that exhibits a large ANE using low-cost and safe elements will be useful to develop a novel energy harvesting technology.

Anomalous transport due to Weyl fermions in the chiral antiferromagnets MnX, X = Sn, Ge.

The recent discoveries of strikingly large zero-field Hall and Nernst effects in antiferromagnets MnX (X = Sn, Ge) have brought the study of magnetic topological states to the forefront of condensed matter research and technological innovation. These effects are considered fingerprints of Weyl nodes residing near the Fermi energy, promoting MnX (X = Sn, Ge) as a fascinating platform to explore the elusive magnetic Weyl fermions. In this review, we provide recent updates on the insights drawn from experimental and theoretical studies of MnX (X = Sn, Ge) by combining previous reports with our new, comprehensive set of transport measurements of high-quality MnSn and MnGe single crystals.

Author Correction: Iron-based binary ferromagnets for transverse thermoelectric conversion.

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

Iron-based binary ferromagnets for transverse thermoelectric conversion.

Thermoelectric generation using the anomalous Nernst effect (ANE) has great potential for application in energy harvesting technology because the transverse geometry of the Nernst effect should enable efficient, large-area and flexible coverage of a heat source. For such applications to be viable, substantial improvements will be necessary not only for their performance but also for the associated material costs, safety and stability. In terms of the electronic structure, the anomalous Nernst effect (ANE) originates from the Berry curvature of the conduction electrons near the Fermi energy.

Comparison of endometriotic cysts and ovarian cancer in association with endometriotic cysts.

Objective: The aim of this study was to clarify the clinical, laboratory, and imaging findings of ovarian cancer in association with endometriotic cysts by detailed comparison of the findings of benign and malignant tumors.

Methods And Materials: This was a retrospective study of 138 women who had an operation for ovarian tumors at the Department of Obstetrics and Gynecology of Kochi Health Sciences Center between September 1, 2011, and July 30, 2015. The ovarian tumors were divided into two groups: the benign group (endometriotic cysts) and the malignant group (ovarian cancer in association with endometriotic cysts).

Erythroblastosis of the Donor Twin of Twin Anemia-Polycythemia Sequence.

Twin anemia-polycythemia sequence (TAPS) is a group of disorders in monochorionic twins characterized by a large intertwin hemoglobin difference without amniotic fluid discordance. Reticulocyte count is used to diagnose this condition, but little is known about the role of erythroblasts, which are the prior stage of reticulocytes. In the present case of TAPS, the 25-yr-old Japanese mother showed no signs of oligohydramnios or polyhydramnios throughout gestation.