2025/11/06(Thu) 14:30 -16:00 一樓演講廳 1F, Auditorium
Title
Quantum Materials: Exploring Novel Properties Through Condensed Matter Physics
Speaker
雷曼研究副技師 (中央研究院物理研究所) Dr. Sankar Raman (Institute of Physics, Academia Sinica)Abstract
Quantum materials lie at the heart of modern condensed matter research, offering an extraordinary platform to study emergent quantum phenomena driven by topology, strong electron correlations, spin–orbit coupling, and reduced dimensionality. Quantum materials have attracted extensive attention due to their novel physical properties. On one hand, these materials provide new platforms for fundamental physics research; on the other hand, they show great potential for device applications based on Quantum physics. In the field of condensed matter physics, research on Quantum materials is mainly carried out in two ways: (i) discovering new experimental phenomena and physical problems in known topological materials, and (ii) predicting, exploring, and synthesizing new types of topological material systems. In either case, obtaining high-quality single crystals is of critical importance, as they provide the necessary foundation for experimental techniques such as angle-resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy/spectroscopy (STM/STS), and quantum oscillation measurements under magnetic fields.In this colloquium, I will present our recent advances in the discovery, synthesis, and characterization of high-quality single crystals of PbTaSe2, PbTaS₂, and NaAlSi—model systems for exploring topological superconductivity and nontrivial band topology. Through combined transport, magnetization, and spectroscopic studies, we reveal evidence of unconventional superconductivity with strong spin–orbit coupling and possible Majorana surface states, making these compounds promising candidates for quantum computation and spintronic applications. In parallel, we have investigated Na₂Co2TeO6, RuCl3 and MnBr3 a proximate Kitaev quantum spin liquid, using temperature- and field-dependent Raman spectroscopy. The results uncover a broad magnetic continuum and strong spin–lattice coupling, pointing toward fractionalized excitations and bond-directional exchange interactions in honeycomb cobaltates. Furthermore, our work on the polar ferrimagnet Cu2OSeO3, ZnₓFe₂₋ₓMo₃O₈ demonstrates magnetic control of chiral phonons using helicity-resolved Magneto-Raman spectroscopy. We observe giant zero-field splitting of E₂ chiral phonon modes and field-induced Zeeman effects, directly linking phonon angular momentum with magnetization and revealing a new mechanism of chiral-selective magnon–phonon coupling. Beyond these materials, our ongoing efforts extend to van der Waals magnets (NiI2, NiPS3, FePS3) and two-dimensional hybrid perovskites, where strain, gating, and dimensional confinement offer powerful means to manipulate magnetic, electronic, and excitonic properties. Using integrated approaches—including crystal growth, quantum transport, magnetometry, and advanced optical probes—we aim to establish microscopic structure–property relationships and identify pathways to engineer quantum phase transitions. Together, these studies provide fundamental insights into how topology, magnetism, and lattice dynamics intertwine in real materials and open new directions toward designing next-generation quantum devices that harness topological superconductivity, chiral phononics, and spin–orbit-entangled states.
Poster
Language
演講語言 (Language): in English