yrammuS 要概bic PbSe. The phase boundary between the 2D and 3D structures was induced in (Pb0.5Sn0.5)Se bulk polycrys-tals synthesized by 2-step process composed of high-temperature solid state reaction and thermal quenching from high temperature. The (Pb0.5Sn0.5)Se bulk showed the 3D to 2D structural phase transition by changing temperature. Through the structure transition, the 1/2.9-times decrease of lattice thermal conductivity (κlat) was observed by strong phonon scattering in the 2D layered structure, and the electronic thermal conductivity (κele) was also decreased by 6 orders of magnitude due to the electronic phase transition from a 3D highly conducting state to a 2D semiconducting state. The total κ modulation ratio = 3.6 was attained at 373 K.光照射による磁化制御が高速かつ高エネルギー効率な磁気記録手法として注目を集めている．最近，強磁性体/重金属薄膜において円偏光が誘起する電子スピンまたは有効磁場の効果が報告された．光誘起電子スピンまたは有効磁場によって強磁性体薄膜の磁化にトルクを与える「光スピントルク」を観測することができる．従来観測されてきた確率的過程の円偏光誘起磁化反転とは対照に，「光スピントルク」を使うことによって超高速に磁化を制御でき高速・高エネルギー効率な光磁気記録が期待できる．本研究では強磁性体/重金属薄膜を用いた「光スピントルク」の起源の解明，ならびに磁化反転応用に向けた実験スキームを検討した．Optical manipulation of magnetization has been attracted much attention for fast and energy-efficient magnetic recording. Recently, generation of electron spins and effective magnetic field induced by irradiation of circularly polarized light has been reported. This optically-induced electron spins and effective magnetic field can be used to excite torque on magnetization in ferromagnetic thin film, which we term optical spin torque. Ultrafast and ener-gy-efficient optical magnetic recording can be expected by using optical spin torque contrary to stochastic circular-ly polarized light induced magnetization switching reported so far. In this study, optical spin torque in ferromagnet/heavy metal bilayers is studied in detail and scheme for optically-induced magnetization switching is considered.近年，キラル分子によるスピン選択性：Chiral-induced Spin-selectivity (CISS)効果が発見され，有機分子による強磁性体や外部磁場の不要な新たな電流-スピン流変換原理の可能性が示された．しかしながら，これまでに実現されているスピン偏極率は最高でも60％程度に留まっている．本研究では，キラル分子と導伝性ナノ構造体を超格子化し，ここを流れる電流に対し複数回のCISS効果，すなわち“多重CISS効果”を与えることで，高いスピン偏極率を有するスピン偏極電流の生成に成功した．The recent finding of spin-selective electron transport through chiral molecules, i.e., the so-called chirality-in-duced spin selectivity (CISS) effect, suggests an alternative method of using organic materials as spin filters for spintronics applications. However, the maximum spin polarization (SP) through the chiral monolayer at room temperature was ≈60%. Here, we introduce a novel method to realize high SP by introducing molecular chirali-ty into conductive nano-materials. The electrons conducted through this multilayered structure undergo multiple tunneling processes through the chiral molecules, that is, multiple CISS effects are activated in the materials.飯浜 賢志60Satoshi IIHAMA須田 理行61Masayuki SUDA極薄強磁性/非磁性ヘテロ接合における光スピントルクを利用した高効率光磁気記録（2021採択）All-optical magnetic recording using optical spin torque in a ultrathin ferromagnet/heavy metal heterostructure(Project 2021)キラル分子修飾ナノ粒子の超格子結晶化による革新的電流-スピン流変換材料の創製（2021採択）Development of novel charge-to-spin current converter based on a superlattice crystal of chiral molecule-modified nanoparticles(Project 2021)55Rep. Grant. Res., Asahi Glass Foundation (2023)
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