QUANTUM MATERIALS

Quantum materials is an emerging field that umbrellas a wide range of fascinating materials where the collective behaviors are much more than the defining characters of the individual constituents. This broad field expands a vast range of materials that exhibit properties arising from strongly interacting electrons and or from topology. Our group is interested in probing materials such as high temperature superconductors, heavy fermion systems, charge density wave systems, topological materials, transition metal dichalcogenides, etc.

For further reading, refer to the special issue of Nature Physics and Nature Materials on Quantum Materials as well as recent reviews on iron-based superconductors.

 

SPECTROSCOPY TOOLS

To probe the fundamental physics of quantum materials, we use mainly two very complementary types of experimental probes, both of which shine light unto the sample. The first technique, angle-resolved photoemission spectroscopy (ARPES) measures the electrons that are kicked out from the materials by the probing light. The second technique, x-ray scattering, measures the light that comes out of the sample due to the incoming photons. While ARPES measures the single-particle spectral function, X-ray scattering measures the particle-particle collective excitations.

 

Angle-Resolved Photoemission Spectroscopy (ARPES)

Based on the photoelectric effect, the ARPES technique directly images the energy- and momentum-resolved electronic states of matter. At the fundamental level, ARPES is the most direct probe for unveiling the basic electronic structure of a material, which is the basis for governing the macroscopic properties of a material. Importantly and furthermore, ARPES can also reveal interaction effects on the electronic states, originating from electron-lattice coupling, electron-electron interactions, and other emergent orders. For further reading, refer to reviews (RMP2003, ARCMP2012) on the technique of ARPES and its application on quantum materials.

 

X-Ray Scattering

A variety of x-ray scattering techniques are available for probing quantum materials, such as elastic and inelastic x-ray scattering, both on and off element-specific resonances of the material. By understanding the difference of the outcoming photons with that of the incident photons, one can infer important information on the kind of fundamental processes that occurred when the light interacted with the materials.

 

 

 

Sponsors

We are grateful to the following funding agencies for sponsoring our research: