We used electron spin resonance (ESR) combined with scanning tunneling microscopy (STM) to measure hydrogenated Ti (spin-1/2) atoms at low-symmetry binding sites on MgO in vector magnetic fields. We found strongly anisotropic g-values in all three spatial directions. Interestingly, the amplitude and lineshape of the ESR signals are also strongly dependent on the angle of the field. We conclude that the Ti spin is aligned along the magnetic field, while the tip spin follows its strong magnetic anisotropy. Our results show the interplay between the tip and surface spins in determining the ESR signals and highlight the precision of ESR-STM to identify the single atom's spin states.
@article{arxiv.2103.09582,
title = {Spin Resonance Amplitude and Frequency of a Single Atom on a Surface in a Vector Magnetic Field},
author = {Jinkyung Kim and Won-jun Jang and Thi Hong Bui and Deung-jang Choi and Christoph Wolf and Fernando Delgado and Denis Krylov and Soonhyeong Lee and Sangwon Yoon and Christopher P. Lutz and Andreas J. Heinrich and Yujeong Bae},
journal= {arXiv preprint arXiv:2103.09582},
year = {2021}
}