Quantum materials in extreme conditions: From high-TC superconductors to quantum magnets

A central challenge in the study of quantum materials lies in disentangling the effects of a complex landscape of competing and coexisting states of matter. To map out the phase diagrams of quantum materials, experiments need to be conducted using a variety of tuning parameters, such as temperature, magnetic field, and pressure. Scientific breakthrough is often achieved as these tuning parameters are pushed to their extremes. In this talk, I will discuss our recent studies on underdoped cuprates and quantum magnets in high magnetic fields and low temperatures. In the case of cuprates, we studied stripe-ordered La-214, which feature very low zero-field superconducting transition temperatures. This enabled us to explore a previously inaccessible energy scale window in underdoped cuprates. Our results established a complete vortex phase diagram of the underdoped striped cuprates, provided much-needed transport signatures of an elusive state of matter called pair density wave, and revealed a novel high-field normal state characterized by the vanishing Hall coefficient. For quantum magnet, we studied the Shastry-Sutherland system SrCu2(BO3)2 (SCBO), which is a valence bond solid. Here we reported the discovery of emergent bound states and impurity pairs in doped SCBO, offering insights into the nontrivial effects of impurities in quantum spin systems. In the end, I will discuss my future research plans, thoughts on capability development, and ideas for funding proposals.

Host: Yasu Takano