Magnetic remanence in single atoms

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Information

Background:

• Permanent magnets store information via magnetic remanence.
• Achieving magnetic remanence at the single-atom level is a key goal for information technology.
• Previous single-atom systems often lacked sufficient stability for practical applications.

Purpose of the Study:

• To investigate the magnetic properties of individual holmium atoms on ultrathin MgO layers.
• To determine the conditions for achieving stable magnetic remanence in single atoms.
• To explore the potential of single-atom magnetism for data storage.

Main Methods:

• Adsorption of individual holmium (Ho) atoms onto ultrathin MgO(100) layers on a Ag(100) substrate.
• Measurement of magnetic properties using techniques sensitive to single-atom behavior (e.g., scanning tunneling microscopy).
• Analysis of magnetic relaxation times and remanence as a function of temperature.

Main Results:

• Individual Ho atoms on MgO exhibit magnetic remanence up to 30 Kelvin.
• A relaxation time of 1500 seconds was observed at 10 Kelvin.
• The observed stability is attributed to a symmetry-protected magnetic ground state.
• Decoupling of the Ho spin from the Ag substrate via the MgO tunnel barrier enhances stability.

Conclusions:

• Single holmium atoms on MgO/Ag(100) demonstrate robust magnetic remanence.
• This system represents a significant advancement in single-atom magnetism.
• The findings pave the way for developing atomic-scale information storage devices.