Jay Qu

All Publications

• Development of deflector mode for spin-resolved time-of-flight photoemission spectroscopy. The Review of scientific instruments Han, X., Qu, J., Sakamoto, S., Liu, D., Guan, D., Liu, J., Li, H., Rotundu, C. R., Andresen, N., Jozwiak, C., Hussain, Z., Shen, Z. X., Sobota, J. A. 2023; 94 (10)

  Abstract

  Spin- and angle-resolved photoemission spectroscopy ("spin-ARPES") is a powerful technique for probing the spin degree-of-freedom in materials with nontrivial topology, magnetism, and strong correlations. Spin-ARPES faces severe experimental challenges compared to conventional ARPES attributed to the dramatically lower efficiency of its detection mechanism, making it crucial for instrumentation developments that improve the overall performance of the technique. In this paper, we demonstrate the functionality of our spin-ARPES setup based on time-of-flight spectroscopy and introduce our recent development of an electrostatic deflector mode to map out spin-resolved band structures without sample rotation. We demonstrate the functionality by presenting the spin-resolved spectra of the topological insulator Bi2Te3 and describe in detail the spectrum calibrations based on numerical simulations. By implementing the deflector mode, we minimize the need for sample rotation during measurements, hence improving the overall efficiency of experiments on small or inhomogeneous samples.

  View details for DOI 10.1063/5.0168447

  View details for PubMedID 37850856

• Reversal of spin-polarization near the Fermi level of the Rashba semiconductor BiTeCl NPJ QUANTUM MATERIALS Qu, J., Han, X., Sakamoto, S., Jia, C. J., Liu, J., Li, H., Guan, D., Zeng, Y., Schuler, M., Kirchmann, P. S., Moritz, B., Hussain, Z., Devereaux, T. P., Shen, Z., Sobota, J. A. 2023; 8 (1)

  View details for DOI 10.1038/s41535-023-00546-x

  View details for Web of Science ID 000941936700001

• The development of microfabricated solenoids with magnetic cores for micromagnetic neural stimulation. Microsystems & nanoengineering Khalifa, A., Zaeimbashi, M., Zhou, T. X., Abrishami, S. M., Sun, N., Park, S., Šumarac, T., Qu, J., Zohar, I., Yacoby, A., Cash, S., Sun, N. X. 2021; 7: 91

  Abstract

  Electrical stimulation via invasive microelectrodes is commonly used to treat a wide range of neurological and psychiatric conditions. Despite its remarkable success, the stimulation performance is not sustainable since the electrodes become encapsulated by gliosis due to foreign body reactions. Magnetic stimulation overcomes these limitations by eliminating the need for a metal-electrode contact. Here, we demonstrate a novel microfabricated solenoid inductor (80 µm × 40 µm) with a magnetic core that can activate neuronal tissue. The characterization and proof-of-concept of the device raise the possibility that micromagnetic stimulation solenoids that are small enough to be implanted within the brain may prove to be an effective alternative to existing electrode-based stimulation devices for chronic neural interfacing applications.

  View details for DOI 10.1038/s41378-021-00320-8

  View details for PubMedID 34786205

  View details for PubMedCentralID PMC8589949