◇ 연사 : Norwegian University of Science and Technology(NTNU), Chul-Hee Min

◇ 일시 : 2026년 8월 4일 10시 30분

◇ 장소 : 자연과학대학 4호관 215호

◇ 주제 : Full-Zone In-plane Spin-Texture Mapping by Momentum  Microscopy and Holstein Polarons in Mixed-Valent TmSe₁₋ₓTeₓ

◇ 초록 : This talk is divided into two parts. In the first, I introduce a laser-based spin-ARPES  instrument combining a 6 eV continuous-wave laser with full polarization control and  a momentum microscope equipped with a 2D imaging spin-filter. This setup enables  simultaneous  acquisition  of  spin-resolved  photoelectron  intensities  across  the  entire  k x–k y plane, drastically reducing measurement times compared to conventional pointby-point spin detectors. I demonstrate full in-plane spin-texture maps across multiple  Brillouin zones on Bi₂Cu/Cu(111) and Sb(111) as benchmark systems. In the second  part,  I  present  the  first  spectroscopic  evidence  of  Holstein  polarons  in  mixed-valent  TmSe₁₋ₓTeₓ. High-energy-resolution photoemission using hard X-ray (6 keV) and XUV  (110 eV) excitation reveals anomalous spectral lineshapes in the semimetallic phase  that  are  quantitatively  reproduced  within  the  Holstein  polaron  model,  establishing  electron–phonon coupling as an essential ingredient for understanding quasiparticle  formation in rare-earth mixed-valent systems.