Quasiparticle dynamics in quantum materials

About us 

We are a new experimental condensed matter research group working in the area of quantum materials. We strive to identify microscopic interactions and dynamics that essentially stabilize macroscopic quantum phases, such as high-Tc superconductivity, quantized Hall conductivity, 2D electron gas, and heavy-fermion states. We work in close collaboration with theoreticians towards a framework of understanding various quantum materials with a unifying theory. 

What are quantum materials and why should we study them? 

Quantum materials are a class of materials that have at least one of the following ingredients- strong electron correlations, spin-orbit interactions, and non-trivial band topology. In general, quantum mechanics dictates the properties of quantum materials on macroscopic length scales and at elevated temperatures, sometimes even above room temperature. 

Currently, a major problem in quantum computing technology is the decoherence in an entangled network of qubits. This prohibits running a long calculation in a quantum computer. However, quantum materials offer a silver lining. We can achieve highly entangled quasiparticles in quantum materials near phase transitions. Another example of strongly entangled quasiparticles is  Majorana fermions in spin liquid systems. 

Our roadmap

• Materials. We measure quantum materials both in crystalline and in epitaxial thin film forms. In our group, we have the expertise to grow oxide-based thin films and heterostructures using pulsed laser deposition. However, we rely on our collaborators for crystalline samples. 

• Properties. First, we identify the macroscopic quantum states by determining the electric transport and magnetization properties of our samples. In the next step, we access dynamics of lattice (phonons), charge (electron-hole pairs), and spin (magnons) degrees of freedom using polarized Raman scattering. Since Raman scattering probes these dynamics simultaneously, we are able to obtain signatures of fundamental interactions in solids, such as electron-phonon coupling, spin-phonon coupling, and electron-magnon coupling. 

• Manipulation. We use thin-film platforms to manipulate materials' properties by means of substrate-induced epitaxial strain, artificial heterostructure engineering, and charge doping.  We do polarized x-ray absorption spectroscopy at various synchrotron facilities to understand how external stimuli affect the orbital occupancy, magnetic exchange interactions, and charge transfer in artificial thin films and heterostructures. On the other hand, van der Waals (vdW) platforms allow investigating the impact of dimensionality on physical properties, since we can easily achieve disorder-free natural thin films by exfoliating the vdW layers. 

• Theory. We measure both macroscopic and microscopic properties of materials. This allows us to identify the microscopic origins behind the bulk properties of materials.  To this end, we work closely with theoreticians to develop a model that can simulate bulk properties of materials using our experimental results which are sensitive to atomic length scales. We focus on the quantum materials that have the potential to be used in quantum technologies.  

Current research themes

Our current research activity focuses on both thin films and single crystals of quantum materials. We grow oxide-based thin films in our group using the pulsed laser deposition method. One of our long-term goals is to implement vdW technologies in our laboratory to exploit the highly-manipulable nature of the vdW platforms.