高橋 龍之介

Ferroaxial order is characterized by the breaking of mirror symmetry parallel to the crystallographic principal axis, which often originates from spontaneous rotational distortions of the crystal lattice. Such rotational distortions are, by symmetry, allowed to couple to specific phonon modes. However, Raman-active phonons associated with these rotational distortions have not yet been clearly identified on a symmetry-consistent basis. Here, we perform polarization-resolved Raman spectroscopy on the ferroaxial phase of Na2BaNi(PO4)2 single crystals and combine the measurements with first-principles lattice-dynamics calculations. This symmetry-guided analysis enables a comprehensive assignment of Raman-active modes in the ferroaxial phase. Several low-frequency Ag modes exhibit finite linewidth broadening, suggesting that these phonons may be weakly affected by the underlying rotational distortion. These results establish a symmetry-based spectroscopic framework for analyzing phonons associated with rotational distortions in ferroaxial materials and provide a basis for future studies of ferroaxial order in complex oxides.

Ferromagnetic resonance (FMR) is a fundamental technique for probing magnetization dynamics in spintronic and magnetic materials. However, conventional FMR measurements rely on broadband vector network analyzers (VNAs), whose high cost limits accessibility for small laboratories and educational environments. To overcome this barrier, we have developed a compact and low-cost FMR measurement platform - the NanoVNA-FMR system-based on a commercially available NanoVNA. The setup integrates an electromagnet and a coplanar waveguide (CPW) and is fully automated using Python scripts. This enables synchronized magnetic-field sweeping, S-parameter acquisition, and real-time visualization. The system successfully captures clear FMR spectra that exhibit systematic shifts in resonance frequency with increasing magnetic field. The results are in excellent agreement with those obtained using a conventional VNA-based FMR system, confirming the quantitative reliability of the NanoVNA approach. Additionally, a 3D-printed sample holder further reduces overall system cost. These results demonstrate that the NanoVNA-FMR system provides a practical, accurate, and accessible alternative for quantitative magnetic characterization and educational applications.

<jats:p>Rocksalt-type heavy rare earth monoxides REOs (RE = Tb, Dy, Er) were synthesized as single phase epitaxial thin films for the first time. They exhibited metallic electronic states and a much higher <jats:italic>T</jats:italic><jats:sub>C</jats:sub> than the corresponding rare earth nitrides.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Here, an unprecedented phenomenon in which 7‐coordinate lanthanide metallomesogens, which align via hydrogen bonds mediated by coordinated H<jats:sub>2</jats:sub>O molecules, form micellar cubic mesophases at room temperature, creating body‐centered cubic (BCC)‐type supramolecular spherical arrays, is reported. The results of experiments and molecular dynamics simulations reveal that spherical assemblies of three complexes surrounded by an amorphous alkyl domain spontaneously align in an energetically stable orientation to form the BCC structure. This phenomenon differs greatly from the conventional self‐assembling behavior of 6‐coordinated metallomesogens, which form columnar assemblies due to strong intermolecular interactions. Since the magnetic and luminescent properties of different lanthanides vary, adding arbitrary functions to spherical arrays is possible by selecting suitable lanthanides to be used. The method developed in this study using 7‐coordinate lanthanide metallomesogens as building blocks is expected to lead to the rational development of micellar cubic mesophases.</jats:p>

<ns7:p>Background Magneto-optical Kerr effect (MOKE) microscopes are powerful experimental tools to observe magnetic domains in magnetic materials. These devices are, however, typically large, unportable, and expensive (∼ several million yen), and therefore prevent many researchers in the field of materials science from easy access to study real-space images of magnetic domains. Methods To overcome these issues, we utilized data from “The OpenFlexure Project” developed by the University of Bath and the University of Cambridge. The purpose of this project is to make high-precision mechanical positioning of the studied sample available to anyone with a 3D printer, especially for use in microscopes. We built a low-cost and portable MOKE microscope device with a 3D printer. We redesigned the 3D modeling data of an ordinary optical microscope provided by The OpenFlexure project and incorporated additional elements, such as optical polarizers and an electromagnetic coil into the primarily designed microscope that did not originally have these elements. Results We successfully observed magnetic domains and their real-space motions induced by magnetic fields using the palm-sized low-cost MOKE microscope, which costs approximately 30,000 yen in raw materials to construct. Conclusions Our methodology to assemble a low-cost MOKE microscope will enable researchers working in the field of materials science to observe magnetic domains more easily without commercial equipment.</ns7:p>