ASUNARO Grant established, 5 researchers including Assist. Prof. Ryosuke TAKEHARA awarded in first call

Recently, the physical properties associating with topology have been enthusiastically studied in the field of condensed matter physics, the concept of which was first introduced as a vortex forming in two-dimensional (2D) systems. Although the vortices have been discovered in superconducting and superfluid thin films, an electrical vortex structure consisting of electric dipole moments has never been found so far. This is because that it has been difficult to create a material that would realize such a structure. Recently, however, a molecular rotor in which the electric dipole moment upon a scaffold tripodal molecule rotates has been developed. The tripodal molecules are arranged in a nested 2D arrangement to form a 2D molecular rotor system, which is exactly the same structure where the vortex was first introduced. In this study, I'll make an attempt on a first observation of the 2D electrical vortex structure expected to emerge in the molecular rotor assembly. Additionally, since the vortex is an electrical one, direct control of the vortex by an electric field is also expected, and these realizations will provide new insights into the field of topology.

Today's comfortable society and our lives are supported by functional materials that can control electrons and light. The 2D materials discovered in recent years have novel properties not found in conventional 3D materials, so their applications as functional materials are being studied worldwide. One of them is to combine the functionality of 3D and 2D materials. Ideally, the interface between the two should be controlled to be completely clean, but such a transfer method for 2D materials has not yet been established. In this study, I develop an ideal transfer technique using an ultra-high vacuum environment.

Symbiosis is a driving force for biological evolution, as the origin of mitochondria is an alphaproteobacterium that established a symbiotic relationship with a eukaryotic ancestor. Symbiosis between protists (unicellular eukaryotes) and alphaproteobacteria is also found in the termite gut, and the study may capture a phenomenon resembling the early process in that the eukaryotic ancestor established the symbiotic relationship with the mitochondrial ancestor. The purpose of this study is to elucidate the symbiotic ultrastructure of the alphaproteobacteria with protists in the termite gut by electron microscopy with in situ hybridization (EM-ISH), and the symbiotic evolutional mechanism by a genome analysis of the alphaproteobacteria. The EM-ISH analysis reveals an ultrastructure of the symbiotic alphaproteobacteria within the host protist by electron microscopy using a specific probe bound with a colloidal gold. Furthermore, the alphaproteobacteria cells are recovered by micromanipulation, applied to whole genome amplification, and the genome analysis of the alphaproteobacteria can clarify the symbiotic evolutional mechanism.

Ionic conductors, solid with ion conductivity, are essential materials used in various applications such as batteries and chemical sensors. Higher ion conductivities are reported when the size of ionic conductors is small at the nanometer level (Nanoionics phenomenon). The spatial conditions and mechanism of the fast ion conduction shown in the nanoscale remain unexplained.
In this study, we applied single-crystal nanosheets of zirconia (ZrO₂), which is an oxygen ion conductor, to clarify the mechanism of fast ion conduction. The advantages of using nanosheets with a two-dimensional structure are that nanosheets are easily deposited on a substrate, and their conductivity is measure by nanoprobes. In addition, the relationship between nano-space and ionic conduction can be explored by changing the size of the nanosheets.

【Development of single crystal ferromagnetic shape memory alloy with ultra–low defect】
Shape deformation and internal degree of freedom of the ferromagnetic shape memory alloy (FSMA) are manipulatable via magnetic field. Hence, FSMA is considered as a potential material for the high–speed actuators in robots and magnetic cooling applications. NiMnGa alloy is a promising FSMA; however, its high brittleness impedes the practicability. Therefore, in this study, the separators (i.e. S or Bi) were introduced into the polycrystalline NiMnGa alloy intentionally to separate the grains and make the alloy even brittle. The polycrystalline NiMnGa is thereafter mechanically crushed into single crystal powders at elevated temperature. The conventional difficulties such as high defect concentration and complicated procedures for single crystal preparation could be solved by the facile mechanical crushing. The NiMnGa single crystal powders are then utilized for the fabrications of the composites for realizing the high–speed actuators for robots and magnetic cooling applications.