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Li, J.*; Li, X.*; Zhang, Y.*; Zhu, J.*; Zhao, E.*; 古府 麻衣子; 中島 健次; Avdeev, M.*; Liu, P.-F.*; Sui, J.*; et al.
Applied Physics Reviews (Internet), 11(1), p.011406_1 - 011406_8, 2024/03
被引用回数:0 パーセンタイル:0.00(Physics, Applied)The desire for intrinsically low lattice thermal conductivity () in thermoelectrics motivates numerous efforts on understanding the microscopic mechanisms of heat transport in solids. Here, based on theoretical calculations, we demonstrate that -MgAgSb hosts low-energy localized phonon bands and avoided crossing of the rattler modes, which coincides with the inelastic neutron scattering result. Using the two-channel lattice dynamical approach, we find, besides the conventional contribution (70% at 300 K) from particlelike phonons propagating, the coherence contribution dominated by the wavelike tunneling of phonons accounts for 30% of total at 300 K. By considering dual contributions, our calculated room-temperature of 0.64 WmK well agrees with the experimental value of 0.63 WmK. More importantly, our computations give a nonstandard dependence, perfectly explaining the abnormal temperature-trend of in experiment for -MgAgSb. By molecular dynamics simulation, we reveal that the structure simultaneously has soft crystalline sublattices with the metavalent bonding and fluctuating liquid-like sublattices with thermally induced large amplitude vibrations. These diverse forms of chemical bonding arouse mixed part-crystal part-liquid state, scatter strongly heat-carrying phonons, and finally produce extremely low . The fundamental research from this study will accelerate the design of ultralow- materials for energy-conversion applications.
Kim, H.*; 永井 佑紀; Rzsa, L.*; Schreyer, D.*; Wiesendanger, R.*
Applied Physics Reviews (Internet), 8(3), p.031417_1 - 031417_8, 2021/09
被引用回数:9 パーセンタイル:63.89(Physics, Applied)トポロジカル超伝導体の磁束にはマヨラナ束縛状態と呼ばれるものが生じ、そのマヨラナ束縛状態を使うことで量子コンピューティングができることが提案されており、世界中で精力的に研究がなされている。多くの研究において、マヨラナ束縛状態の有無を調べるための磁束のゼロエネルギー束縛状態の観察が行われている。本研究では、ゼロエネルギー束縛状態の観察が行われたとしてもそれがマヨラナ束縛状態ではないということを実験理論両面から示し、これまでのマヨラナ束縛状態の有無の判別法に問題があることをはっきりと示した。本研究により、マヨラナ束縛状態の有無を調べるには慎重な研究が必要であることがわかった。