Home| 題 目 | Spin and valley physics in ferroelectric low-dimensional systems and transition-metal oxide heterostructures |
| 講 師 | Paolo Barone （CNR-SPIN, Italy） |
| 日 時 | 2015年10月23日（金） 16:30- |
| 場 所 | 先端物質科学研究科 402N |
| 要 旨 | Technological advances in future electronics and the design of next-generation devices strongly rely on the investigation of internal quantum degrees of freedom of electrons beside electron charge. Electron spin represents the most-studied case due to its obvious connection with magnetic information storage and to the possibility to design spintronic devices based on spin-splitting phenomena and spin-polarized transport. Another potentially appealing binary degree of freedom has been identified as a valley pseudospin, labeling the degenerate energy extrema in momentum space, which could be used to process information in valleytronics devices. The research in this field has been boosted by the recent discovery of hexagonal 2D materials, such as graphene and transition-metal dichalcogenides, displaying valleys at the corners (K points) of the Brillouin zone. Intrinsic physical properties associated with valley occupancy, such as valley-contrasting magnetic moment, valley Hall effect and valley-selective circular dichroism, emerge only when space-inversion is broken, a condition needed also for the appearance of spin-splitting phenomena driven by the spin-orbit interaction; as such, valley physics could in principle be tuned and manipulated in ferroelectric materials, analogously to what has been recently proposed in Ferroelectric Rashba Semiconductors. I will discuss this possibility in two classes of materials, namely i) in trigonal AB binary monolayers, where A,B belong to group IV or III-V elements, possessing a buckled graphene-like structure and ii) in perovskite oxide heterostructures grown in the [111] direction, where bilayered nanostructures with a similar honeycomb geometry can be realized. By means of a combined ab-initio DFT and model-Hamiltonian approach, I will discuss the coupling of spin and valley physics, their interplay with ferroelectricity and the possible coexistence/interplay with Rashba-like effects that are expected to emerge in such noncentrosymmetric materials. |
| 担 当 | 獅子堂 達也 (先端物質科学研究科) |
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