Graphene interface gives an unusually large, tunable magnetic response
A low-temperature experiment measured large shifts in electronic energy levels where graphene meets a layered magnet. Two spectral peaks moved in the same direction at different rates, and an electric field changed their positions. The peer-reviewed study links that unusual response to interfacial orbital magnetism, while the detailed microscopic interaction remains unresolved.
Science··Morning
Two electronic peaks move together at different rates
A peer-reviewed experiment found an unusually large magnetic response at the contact between graphene and Fe3GeTe2, a layered magnet containing iron, germanium and tellurium. As the applied magnetic field increased, two electronic spectral peaks moved towards higher energies at different rates. The fitted shifts gave approximately 30 and 230 for the effective Landé g factors, numbers that describe the strength of the energy response to a magnetic field.[1]
Graphene opens a view into the buried interface
The magnetic flake was 28 nanometres thick, enclosed by graphene above and graphite below to limit deterioration. Scanning tunnelling microscopy and spectroscopy probed it at approximately 6.1 kelvin. In an energy window where tunnelling into graphene was suppressed, current could still reach the metallic material underneath. Peaks extended across the surface, rather than appearing only at individual defects. Comparable peaks were absent in bulk samples taken from that crystal batch, supporting an origin at the interface.[1]
An electric field changes the peak positions
Moving the microscope tip altered the interface’s electric field and shifted the peaks while the magnetic field remained at 2 tesla. Even at 3 tesla, the largest accessible field, the response had not saturated. Calculations and measurements led the authors to propose interacting orbital contributions, including one associated with tilted local magnetic moments. The detailed interaction remains unresolved. The observed control concerns a low-temperature material interface; the study did not demonstrate an electronic device operating at room temperature.[1]
