Magnetic Topological Critical Materials
Abstract
Topological materials exhibiting symmetry-protected surface states such as topological insulators or bulk band crossings such as Dirac or Weyl semimetals have raised significant interests in condensed matter physics and materials science. The interplay of band topology and magnetism further leads to exotic phenomena like chiral anomaly, axion insulator, anomalous Hall effect, and giant circular photogalvanic signal. Here, we aim to achieve strain-tuned antiferromagnetic to ferromagnetic transition in the magnetic topological system EuCd2As2-xSbx and realize an ideal magnetic Weyl semimetal without magnetic field. Second, we will use strain to induce topological transition between trivial insulator and Dirac semimetal in the non-magnetic system SrCd2As2-xSbx. Third, we will demonstrate strain-tunable topological magnetic transport phenomena, including the anomalous Hall and chiral magnetic effects. Last, we will measure unique electron dynamics of a Weyl semimetal stabilized by spin fluctuations in the paramagnetic phase. To achieve these objectives, our team with complementary expertise will adopt integrated experimental and computational approaches. In particular, we will grow single crystals of the above materials by flux and vapor transport techniques. We will measure their transport and other properties in piezoelectric-based strain devices, high-pressure diamond anvil cells, and ultrafast experiments. In addition, we will perform first-principles density functional theory calculations to predict and interpret the experiments. We expect our outcomes to address several outstanding challenges in this field, such as precisely controlling magnetic chiral effect in topological semimetals, switching on demand gapless and gapped magnetic topological phases without magnetic field, distinguishing the effects of band topology from magnetism, and separating Berry curvature contributions to the anomalous Hall effect. The success of this program will help develop next-generation devices based on magnetic topological materials, with applications in quantum metrology, low-energy consumption spintronics, and optoelectronic applications. They serve as the cornerstones of quantum technologies that are critical to the DOD mission.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 10, 2022
- Source ID
- FA23862114060XX0
Entities
People
- Cheng-chien Chen
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Alabama at Birmingham