專題演講

2018/01/26(Fri)     15:00 -16:30    1st Floor(P101 meeting room)

Title

Spin orbit interaction in photoexcited states: High resolution two-photon photoemission

Speaker

Dr. Ryuichi Arafune

International Center for Materials Nanoarchitectonics (MANA)

Abstract

Spin-orbit interaction (SOI) is one of the most fundamental interaction and plays a key role in spintronics that aims at controlling the spin characteristics. Spintronics is developing exclusively in solid state physics. In surface science, SOI is also one of the most interested topics, because unique electronic characters arising from SOI appears on surfaces and low dimensional systems. Among many techniques for spin control via SOI proposed in spintronics, optical manners are fascinating because of highly accurate and fast control. They also enable us to manipulate the spin without magnetic materials. Thus, ‘Opto-spintronics’ has been paid much attention as a new branch of spintronics. It is important to understand SOI in the photoexited (unoccupied) states for manipulating the spin by light. Despite its importance, the spin-texture due to SOI in the unoccupied states has hardly been measured.
In this talk, I will show our recent results about SOI in the image potential states, which is the representative unoccupied state at surfaces, measured by using high resolution two-photon photoemission (2PPE) spectroscopy. First, I’ll show that the high resolved 2PPE data reveals the appearance of the Rashba-type spin splitting in the image potential states as well as in the Shockley surface states in the occupied region. We have found that the reversal of the spin-textures in the high order (n≥2) image potential states. After that, I’ll present a spectroscopic demonstration about switching the spin-related current by light.