Superheavy elements (SHEs) with atomic numbers greater than 100 are expected to have interesting chemical properties that differ from those anticipated by the Periodic Table caused by strong relativistic effects. The SHEs must be produced in heavy-ion induced nuclear reactions and are only available on a single atom scale at a time. The difficulty of the experiments, therefore, still causes uncertainty about their chemical properties and remains things to be further investigated. In recent years, several fascinating studies have been reported: the atomic structure of lawrencium (Lr, element 103) by measuring the first ionization potential, co-precipitation of rutherfordium (Rf, element 104), the volatility of dubnium (Db, element 105) compounds, and formation of the hexacarbonyl compound of seaborgium (Sg, element 106). Here we briefly review recent highlighted results of chemical studies on SHEs. Future prospects of these challenging research subjects are briefly discussed.

Magnons, namely spin waves, are collective spin excitations in ferromagnets, and their control through coupling with acoustic phonons is crucial for future hybrid technologies. Their hybridized states, magnon polarons, host both magnonic and phononic advantages such as magnetic tunability and long coherence for magnons. However, SAW-based magnomechanical systems have realized weak interaction due to their traveling acoustic waves, thus limiting generation of magnomechanical phenomena such as magnon polarons. We develop a cavity magnomechanical system enabling the hybrid interaction to be enhanced by confining SAWs in an acoustic cavity. The low-loss property with acoustic quality factor up to 4,500 results in significant acoustic excitation of spin waves in a ferromagnetic film via magnetostriction. Furthermore, the collective spin motions reversely give back-action force on the cavity dynamics, where acoustic frequency and quality factor are modulated and suppressed. Comparison between experimental and theoretical results reveals that cooperativity exceeds unity, demonstrating coherent transduction magnons and phonons. This novel architecture opens up the possibility to sustain magnon polarons, realizing a new capability of magnons and phonons for classical and quantum signal processing applications.

High-resolution heat capacity measurements at low temperatures in magnetic fields are effective for examining gap structures and the pairing symmetries of superconductivity. Angle-resolved heat capacity measurements under in-plane magnetic fields for a series of molecules-based superconductors have revealed that dimer-Mott type compounds show d-wave paring with line-nodal gap structure. The gap symmetry changes from d_xy wave to d_x²－y²+s_± wave depending on dimerization and frustration of the dimer lattice, even though they are in the same superconducting phase in the dimer-Mott phase diagram. In contrast, a non-dimeric compound shows anisotropic full-gapped behavior. The difference in gap structure can be understood based on the difference in their pairing interactions originating from electron correlations.

The phase-relation between supercooled liquid silicon (l-Si) and amorphous silicon (a-Si) is discussed based on experimental results. Electrostatically levitated l-Si samples were supercooled down to low temperatures, 300 K below the melting temperature (T_cl : 1,687 K) and solidified accompanied with the release of latent heat. It was found that solidified Si samples melted again at 1,480 K caused by the latent heat. Also, it was found that the Si samples rapidly quenched near the solidification temperature contained a large amount of a-Si with the tetrahedral coordination. These two findings show that the supercooled l-Si samples solidified into a-Si and a-Si melted, confirming the idea of a first-order phase transition between two metastable phases proposed by Turnbull et al.