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All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics
Published on: January 19, 2018
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Longitudinal and transverse electron paramagnetic resonance in a scanning tunneling microscope
Tom S Seifert1, Stepan Kovarik2, Dominik M Juraschek2,3
1Department of Materials, ETH Zürich, 8093 Zürich, Switzerland. tom.seifert@mat.ethz.ch sebastian.stepanow@mat.ethz.ch.
Science Advances
|October 1, 2020
Summary
Electron paramagnetic resonance scanning tunneling microscopy (EPR-STM) uses piezoelectric coupling for excitation. This mechanism explains how magnetic field gradients drive different atomic spins, advancing EPR-STM applications.
Area of Science:
- Surface Science
- Quantum Spin Physics
- Spectroscopy
Background:
- Electron paramagnetic resonance (EPR) spectroscopy is a key technique for characterizing paramagnetic materials.
- Combining EPR with scanning tunneling microscopy (STM) has enabled single-spin sensitivity and sub-angstrom resolution.
- The precise excitation mechanism in EPR-STM remains a subject of debate, limiting its broader adoption.
Purpose of the Study:
- To experimentally investigate and model the excitation mechanism of EPR-STM.
- To clarify the role of piezoelectric coupling in EPR-STM for atomic species.
- To explore the potential of EPR-STM for nonpolar species and novel excitation schemes.
Main Methods:
- Experimental study of EPR-STM on Fe and hydrogenated Ti atoms on a MgO surface.
- Modeling of the EPR-STM process using Bloch equations.
- Atomic-multiplet calculations to identify EPR driving forces.
Main Results:
- Results strongly support a piezoelectric coupling mechanism for EPR-STM excitation.
- Observed adiabatic oscillation of EPR species within the STM tip's inhomogeneous magnetic field.
- Identified distinct driving forces: transverse magnetic field gradients for spin-1/2 Ti, longitudinal for spin-2 Fe.
Conclusions:
- The piezoelectric coupling mechanism provides a robust explanation for EPR-STM excitation.
- This mechanism's ability to induce electric dipole moments broadens EPR-STM applicability to nonpolar species.
- The findings pave the way for advanced EPR-STM techniques and nonlinear excitation schemes.
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