Kyungsu Kim

All Publications

• Interstitial-Induced Ferromagnetism in a Two-Dimensional Wigner Crystal. Physical review letters Kim, K. S., Murthy, C., Pandey, A., Kivelson, S. A. 2022; 129 (22): 227202

  Abstract

  The two-dimensional Wigner crystal (WC) occurs in the strongly interacting regime (r_{s}≫1) of the two-dimensional electron gas (2DEG). The magnetism of a pure WC is determined by tunneling processes that induce multispin ring-exchange interactions, resulting in fully polarized ferromagnetism for large enough r_{s}. Recently, Hossain et al. [Proc. Natl. Acad. Sci. U.S.A. 117, 32244 (2020)PNASA60027-842410.1073/pnas.2018248117] reported the occurrence of a fully polarized ferromagnetic insulator at r_{s}≳35 in an AlAs quantum well, but at temperatures orders of magnitude larger than the predicted exchange energies for the pure WC. Here, we analyze the large r_{s} dynamics of an interstitial defect in the WC, and show that it produces local ferromagnetism with much higher energy scales. Three hopping processes are dominant, which favor a large, fully polarized ferromagnetic polaron. Based on the above results, we speculate concerning the phenomenology of the magnetism near the metal-insulator transition of the 2DEG.

  View details for DOI 10.1103/PhysRevLett.129.227202

  View details for PubMedID 36493455

• The quantum Hall effect in the absence of disorder NPJ QUANTUM MATERIALS Kim, K., Kivelson, S. A. 2021; 6 (1)

  View details for DOI 10.1038/s41535-021-00321-w

  View details for Web of Science ID 000625115000001

• Discovery of an insulating ferromagnetic phase of electrons in two dimensions. Proceedings of the National Academy of Sciences of the United States of America Kim, K., Kivelson, S. A. 2021; 118 (2)

  View details for DOI 10.1073/pnas.2023964118

  View details for PubMedID 33408156

• Magnon topology and thermal Hall effect in trimerized triangular lattice antiferromagnet PHYSICAL REVIEW B Kim, K., Lee, K., Chung, S., Park, J. 2019; 100 (6)

  View details for DOI 10.1103/PhysRevB.100.064412

  View details for Web of Science ID 000481609500005