In Pursuit of High Temperature Quantum Anomalous Hall State
Abstract
The quantum anomalous Hall (QAH) state is a topological quantum state with quantized Hall resistance and zero longitudinal resistance in the absence of any external magnetic field. The dissipationless chiral current that flows along the edges of the QAH sample, known as chiral edge state (CES), opens the door to electronics, spintronics and topological quantum computations with low- or even zero-energy dissipation. However, the critical temperature of the QAH state below which the quantization of the anomalous Hall resistance is realized is limited to ~l00mK. This low critical temperature is the main obstacle for exploring new physics and accessing potential applications of this system. This project aims to significantly enhance the critical temperature of the QAH effect by magnetizing the surface states of topological insulators (Tis) through close proximity to a high Curie temperature ferromagnetic insulator (FlvH) (e.g. Tm3Fe5012 (TIG)). High quality TJ/FMI heterostructures will be synthesized using molecular beam epitaxy (MBE) aided by in-situ probes such as reflection high energy electron diffraction (RHEED) and angle-resolved photoemission spectroscopy (ARPES) and systematically studied by the ex-situ electrical transport measurements. In addition, we will also explore the high temperature QAH state in the TI films in proximity to high Neel temperature antiferromagnetic insulator (AFMI) (e.g. Cr203, NiO, MnTe, MnSe, BiFe03 and SrMn03) and also multilayer 1T -WTc2 films on FMI (or AFMI) heterostructures. These heterostructures with QAH state with the enhanced critical temperature will enable us to accurately study three fundamental aspects of the QAH physics: (1) the universal conductivity at the QAH insulator-Anderson insulat6r quantum phase transition point; (2) the scaling behaviors of the-h/e2 plateau to h/e2 plateau transition; and (3) the current-induced breakdown phenomenon. The proposed research will not only advance the basic understanding of the QAH physics, especially the relationship between the QAH state and the well-studied quantum Hall state, but also provide new p1atforms for potentially dissipation-free chiral spintronic devices. Specifically we will explore different schemes to enhance the transmission of the chiral edge state current from our QAH samples with spintronic and other logic devices. The realization of the Ôchiral spintronics will help to usher in a new era of memory and logic device technology with low energy dissipation.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810198
Entities
People
- Cui-Zu Chang
Organizations
- Army Contracting Command
- Pennsylvania State University
- United States Army