Electrical Control of the Quantum Anomalous Hall State
Abstract
(Approved for Public Release)The success of next-generation quantum material-based electronic and spintronic devices hinges on the creation of a reliable material platform with robust and low-energy consumption quantum states that are amenable to easy manipulation and control. Topological states of matter provide an appealing opportunity due to their intrinsic protection against impurity scattering. The quantum anomalous Hall (QAH) state is one example of a topological state. It possesses quantized Hall resistance with spin-polarized dissipationless chiral edge current (CEC). The QAH-CEC chirality is typically controlled by sweeping back and forth an external magnetic field. However, this method is clumsy and cumbersome for practical use in real CEC-based electronic devices. More recently, we have harnessed the spin-orbit torque (SOT) effect generated by bulk and/or surface state carriers to achieve the electrical switching of QAH-CEC chirality. The ability to electrically control theQAH state instantaneously without sweeping the external magnetic field is essential for the development of QAH-based computation and information technologies. In the proposed project, we will both experimentally and theoretically investigate the electrical control of the QAH and axion insulator states and explore the associated quantum phenomena, including magnetic domain wall motion in narrow QAH devices, the detection of the topological magnetoelectric (TME) effect in axion insulators, electrical control of the QAH to axion insulator phase transition, etc. We will adopt two approaches for the electrical control: (1) Based on our recent work, we will leverage the SOT effect generated by CEC to electricallycontrol the magnetization of the QAH insulators and optimize our sample quality to realize the magnetic domain wall motion in narrow QAH devices; and (2) We will synthesize the QAH/axion insulator heterostructures, in which the (topological) magnetoelectric effect in axion insulators (i.e. axion electrodynamics) can be utilized to electrically control the magnetization of QAH insulators and thus the corresponding CEC chirality. We will develop two different experimental strategies to detect the TME effect in axion insulators. Moreover, we will also theoretically develop a systematic understanding of the microscopic mechanism for the SOT in QAH and axion insulators, particularly focusing on the role of the CEC, and the magnetoelectric effect in QAH/axion insulator heterostructures.Both are essential components for achieving the electrical control of the QAH/axion insulator states. Our success in electrical control of the QAH/axion insulator states and the detection of the TME effect will play a key role in advancing topological quantum computations. These breakthroughs hold the potential to disrupt encryption and solve problems that are beyond the capabilities of classical computers and thus will improve the national defense and peacekeeping capabilities of the US Naval Forces as well as other branches of our government.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 08, 2024
- Source ID
- N000142412133
Entities
People
- Cui-Zu Chang
Organizations
- Office of Naval Research
- Pennsylvania State University
- United States Navy