Michael Flatté

Affiliation: The University of Iowa

Research Interests: Nanoscience, Spintronics

Title: Proposal to Probe neV to μeV Dynamic Spin Interactions in a Semiconductor with Spin-Polarized DC Scanning Tunneling Spectroscopy

Abstract: A broad range of quantum-coherent spin centers have been identified in optically-accessible materials, especially including nitrogen-vacancy, silicon-vacancy, and germanium-vacancy centers in diamond, divacancies and transition-metal dopants in several polytypes of silicon carbide, and spin centers in 2D materials such as hexagonal boron nitride. Optical probes usually require these spin centers to be well separated, and for integration electrical control and probing would be desirable; long-lived spin centers have also been found in materials that cannot be easily probed optically. Some of the above materials, such as silicon carbide, allow for good electrical transport.

Coherent properties of spin centers in silicon, i.e. dopants, have been probed for many years using “electrically detected magnetic resonance” (EDMR), an electron spin resonance technique that requires an rf field[1]. Recently, however, it has become clear that dc techniques can electrically manipulate and measure the spin orientations of spin centers through the establishment and release of electrical transport bottlenecks[2]. The key requirements of these approaches are a two-dopant or two-site recombination center and a small magnetic field to beat the spin precession against the other timescales of the system. A major advantage is that no ac field of any type is required.

Recently we have proposed that measurements could be made on a single dopant in the transport path (eliminating the two-dopant requirement above) using a spin-polarized electrical contact and a small transverse magnetic field. Some examples of the potential for this approach will be described, including a proposal to measure, at room temperature, the μeV scale exchange and hyperfine fields between spins in a semiconductor using dc magnetoresistance[3], and a proposal to electrically measure zero-field spin splittings and spin coherence times of divacancies in silicon carbide[4].

This work was supported by DOE DE-SC0016447. I acknowledge collaborations with S. R. McMillan, N. Harmon, D. Fehr, J. Sink, and P. M. Lenahan.