Yimei Zhu1
Brookhaven National Laboratory1
Yimei Zhu1
Brookhaven National Laboratory1
In this presentation I will give an overview of our recent work on probing competing degrees of freedom of charge, orbital and lattice and electron-phonon coupling in strongly correlated quantum materials using ultrafast electron diffraction and microscopy. Two examples will be given. 1) Using fs temporal gating via photoinduced nearfield electron microscopy (two-color PINEM) to achieve 10<sup>-21</sup> m●s spatiotemporal resolution to probe nanoscale-femtosecond dielectric response and metal-to-insulator transition in VO2. 2) Probing photoinduced electronic transition from a topological insulating state to a Dirac semimetal state in ZrTe5 using MeV ultrafast electron diffraction. I will also report our latest development on the laser-free electron pulser that can be retrofitted into a commercial transmission electron microscope for ultrafast stroboscopic diffraction, imaging and GHz excitations. I will show an example of the interdigitated comb device that is widely used as an antenna or sensor in mobile platforms for direct visualization of its interactions with microwave and electromagnetic wave dynamics. The ability to probe materials dynamic responses under RF and microwave excitations has promising applications for qubit devices and quantum information science.<br/><br/>Collaborations with X. Fu, T. Konstantinova and other co-authors listed in the references below are acknowledged. Work at BNL was supported by the DOE-BES-MSE grant DE-SC0012704.<br/><br/>References:<br/>1. X. Fu, F. Barantani, …. and Y. Zhu, "Nanoscale-femtosecond dielectric response of Mott insulators captured by two-color near-field UEM ", Nat. Comm., 11:5770 (2020).<br/>2. T. Konstantinova, L. Wu, … and Y. Zhu, "Photoinduced chiral Dirac semimetal in ZrTe5", npj Quantum Materials, 5:80, 1-8 (2020).<br/>3. X. Fu, E. Wang, …. and Y. Zhu, "Laser-free ultrafast electron microscopy of electromagnetic wave dynamics", Sci. Adv., 6 eabc3456 (2020).