Title: Deciphering the Enigma of Quantum Materials by X-ray Scattering and Spectroscopy

Place : E6-2(Natural Science B/D). 1st fl. #1323

[Zoom 회의 참가]

The advent of modern synchrotron radiation facilities provides new powerful experimental tools to study quantum-mechanical phenomena that emerge in condensed matter. Especially, the rapid development of various x-ray scattering and spectroscopy techniques allows us to unveil the hidden clues to longstanding puzzles in strongly-correlated materials where the complex interplay of charge, spin, orbital, and lattice degree of freedom often leads to counter-intuitive phenomena. In this talk, I will introduce our recent attempts to decipher the enigma of correlated quantum materials. First, the omnipresence of charge density waves (CDWs) across almost all cuprate material families underpins a common organizing principle. However, a longstanding debate of whether its spatial symmetry is a unidirectional stripe or bidirectional checkerboard remains unresolved. We take two different strategies to unequivocally reveal the unidirectional nature of CDWs in cuprate superconductors [1-3]. Second, the recent realization of the superconducting phase in infinite-layer nickelate materials provides an excellent platform to find the essential ingredient for high-temperature superconductivity by comparing it to cuprates. We established an analogy between cuprates and nickelates superconductors by observing collective excitations such as CDW or low-energy magnon [4-6]. Lastly, our recent efforts to applying x-ray scattering and spectroscopy techniques to a broader range of quantum materials, such as topological semimetals and battery-related materials will be briefly introduced. These examples show great potential of x-ray scattering and spectroscopy to provide new insights for fundamental understanding of quantum materials.