Year: 2026
Type: preprint
Abstract: Point defects have been successfully utilized in various quantum technologies, serving as quantum qubits for quantum computation, single-photon emitters for quantum communication, and nanoscale sensors for quantum metrology. However, their further development faces key challenges, particularly in discovering and exploring suitable defect-host systems that meet the necessary criteria for quantum applications. Here, using polarization-resolved Raman spectroscopy and terahertz absorption spectroscopy, we discover three distinct chromium-vacancy-induced excitations in the uniaxial antiferromagnetic insulator, Cr$_2$O$_3$. These vacancy-induced excitations have an energy scale of a few tens of millielectronvolts and are twofold degenerate, and the lowest one at 64 $cm^{-1}$ is sharp and sensitive to the external magnetic field along the easy-axis direction, particularly close to the spin-flop regime around 6T, where the mode softens from 64 to 27$cm^{-1}$. Based on the defect supercell first-principles calculations, we interpret the mode at 64 $cm^{-1}$ as a local magnetic excitation of the local moment within the chromium vacancy state. Our results establish that the magnetic defect states in Cr$_2$O$_3$ have potential for quantum applications.
Source: arXiv (Cornell University)
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1269357381, G1453181110, NSF-BSF: Spectroscopy of excitonic insulators with direct gap, Track 4: Advanced CI Coordination Ecosystem: Monitoring and Measurement Services, G2764489136, G2790447815, G3406661761, G3562386289, Track 1: ACCESS Resource Allocations Marketplace and Platform Services (RAMPS), G4010157413, ACO: An Open CI Ecosystem to Advance Scientific Discovery (OpenCI), G4888654661, G5019522989, Track 3: COre National Ecosystem for CyberinfrasTructure (CONECT), G5212984984, G5367127336, G5464919783, G5531675157, G6112577764, G6121277264, G6214533599, G6563462483, G6926000687, G6965887028, G8174472116, Track 2: Customized Multi-tier Assistance, Training, and Computational Help (MATCH) for End User ACCESS to CI, G8684305011, G8815868726
OpenAlex ID: W7206175233