Papers on arXiv
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Journal Papers

50. Classification of magnetic order from electronic structure by using machine learning
Yerin Jang, Choong H. Kim*, and Ara Go* (*: correspondence)
Sci. Rep. 13, 12445 (01 Aug 2023) [arXiv:2302.13329]
Identifying the magnetic state of materials is of great interest in a wide range of applications, but direct identification is not always straightforward due to limitations in neutron scattering experiments. In this work, we present a machine-learning approach using decision-tree algorithms to identify magnetism from the spin-integrated excitation spectrum, such as the density of states. The dataset was generated by Hartree-Fock mean-field calculations of candidate antiferromagnetic orders on a Wannier Hamiltonian, extracted from first-principle calculations targeting \boo. Our machine learning model was trained using various types of spectral data, including local density of states, momentum-resolved density of states at high-symmetry points, and the lowest excitation energies from the Fermi level. Although the density of states shows good performance for machine learning, the broadening method had a significant impact on the model's performance. We improved the model's performance by designing the excitation energy as a feature for machine learning, resulting in excellent classification of antiferromagnetic order, even for test samples generated by different methods from the training samples used for machine learning.
49. Tuning orbital-selective phase transitions in a two-dimensional Hund’s correlated system
Eun Kyo Ko, Sungsoo Hahn, Changhee Sohn, Sangmin Lee, Seung-Sup B. Lee, Byungmin Sohn, Jeong Rae Kim, Jaeseok Son, Jeongkeun Song, Youngdo Kim, Donghan Kim, Miyoung Kim , Choong H. Kim*, Changyoung Kim*, Tae Won Noh* (*: correspondence)
Nat. Commun. 14, 3572 (16 Jun 2023) [arXiv:2210.05621]
Hund’s rule coupling (J) has attracted much attention recently for its role in the description of the novel quantum phases of multi-orbital materials. Depending on the orbital occupancy, J can lead to various intriguing phases. However, experimental confirmation of the orbital occupancy dependency has been difficult as controlling the orbital degrees of freedom normally accompanies chemical inhomogeneities. Here, we demonstrate a method to investigate the role of orbital occupancy in J related phenomena without inducing inhomogeneities. By growing SrRuO3 monolayers on various substrates with symmetry-preserving interlayers, we gradually tune the crystal field splitting and thus the orbital degeneracy of the Ru t2g orbitals. It effectively varies the orbital occupancies of two-dimensional (2D) ruthenates. Via in-situ angle-resolved photoemission spectroscopy, we observe a progressive metal-insulator transition (MIT). It is found that the MIT occurs with orbital differentiation: concurrent opening of a band insulating gap in the dxy band and a Mott gap in the dxz/yz bands. Our study provides an effective experimental method for investigation of orbital-selective phenomena in multi-orbital materials.
48. Heteroepitaxial control of Fermi liquid, Hund metal, and Mott insulator phases in the single-atomic-layer limit
Jeong Rae Kim, Byungmin Sohn, Hyeong Jun Lee, Sangmin Lee, Eun Kyo Ko, Sungsoo Hahn, Sangjae Lee, Younsik Kim, Donghan Kim, Hong Joon Kim, Youngdo Kim, Jaeseok Son, Charles H. Ahn, Frederick J. Walker, Ara Go, Miyoung Kim, Choong H. Kim*, Changyoung Kim*, Tae Won Noh* (*: correspondence)
Advanced Materials, 2208833 (05 Feb 2023) [arXiv:2203.04244]
47. Extended oxygen octahedral tilt proximity near oxide heterostructures
Junsik Mun, Eun Kyo Ko, Baekjune Kang, Byeongjun Gil, Choong H. Kim, Sungsoo Hahn, Jeongkeun Song, Yimei Zhu, Changhee Sohn, Tae Won Noh, and Miyoung Kim
Nano Letters, 23, 1036 (30 Jan 2023)

46. Ferroelectricity-driven phonon Berry curvature and nonlinear phonon Hall transports
Jino Im†, Choong H. Kim†*, and Hosub Jin* (†:co-first,*: correspondence)
Nano Letters 22, 8281 (4 Oct 2022) [arXiv:2209.10769]
Berry curvature (BC) governs topological phases of matter and generates anomalous transport. When a magnetic field is applied, phonons can acquire BC indirectly through spin-lattice coupling, leading to a linear phonon Hall effect. Here, we show that polar lattice distortion directly couples to a phonon BC dipole, which causes a switchable non-linear phonon Hall effect. In a SnS monolayer, the in-plane ferroelectricity induces a phonon BC and leads to the phononic version of the non-volatile BC memory effect. As a new type of ferroelectricity-phonon coupling, the phonon Rashba effect emerges and opens a mass-gap in tilted Weyl phonon modes, resulting in a large phonon BC dipole. Furthermore, our ab initio non-equilibrium molecular dynamics simulations reveal that non-linear phonon Hall transport occurs in a controllable manner via ferroelectric switching. The ferroelectricity-driven phonon BC and corresponding non-linear phonon transports provide a novel scheme for constructing topological phononic transport/memory devices.
45. Signature of Kondo hybridisation with an orbital-selective Mott phase in 4d Ca2−xSrxRuO4
Minsoo Kim, Junyoung Kwon, Choong H. Kim, Younsik Kim, Daun Chung, Hanyoung Ryu, Jongkeun Jung, Beom Seo Kim, Dongjoon Song, Jonathan D. Denlinger, Moonsup Han, Yoshiyuki Yoshida, Takahashi Mizokawa, Wonshik Kyung, and Changyoung Kim
npj Quantum Materials 7, 59 (8 Jun 2022)
The heavy fermion state with Kondo-hybridisation (KH), usually manifested in f-electron systems with lanthanide or actinide elements, was recently discovered in several 3d transition metal compounds without f-electrons. However, KH has not yet been observed in 4d/5d transition metal compounds, since more extended 4d/5d orbitals do not usually form flat bands that supply localised electrons appropriate for Kondo pairing. Here, we report a substitution- and temperature-dependent angle-resolved photoemission study on 4d Ca2−xSrxRuO4, which shows the signature of KH. We observed a spectral weight transfer in the γ-band, reminiscent of an orbital-selective Mott phase (OSMP). The Mott localised γ-band induces the KH with an itinerant β-band, resulting in spectral weight suppression around the Fermi level. Our work demonstrates the evolution of the OSMP with possible KH among 4d electrons, and thereby expands the material boundary of Kondo physics to 4d multi-orbital systems.
44. Defect-gradient-induced Rashba effect in van der Waals PtSe2 layers
Junhyeon Jo†, Jung Hwa Kim†, Choong H. Kim†, Jaebyeong Lee, Daeseong Choe, Inseon Oh, Seunghyun Lee, Zonghoon Lee, Hosub Jin, and Jung-Woo Yoo (†: co-first)
Nat. Commun. 13, 2759 (19 May 2022)
Defect engineering is one of the key technologies in materials science, enriching the modern semiconductor industry and providing good test-beds for solid-state physics. While homogenous doping prevails in conventional defect engineering, various artificial defect distributions have been predicted to induce desired physical properties in host materials, especially associated with symmetry breakings. Here, we show layer-by-layer defect-gradients in two-dimensional PtSe2 films developed by selective plasma treatments, which break spatial inversion symmetry and give rise to the Rashba effect. Scanning transmission electron microscopy analyses reveal that Se vacancies extend down to 7 nm from the surface and Se/Pt ratio exhibits linear variation along the layers. The Rashba effect induced by broken inversion symmetry is demonstrated through the observations of nonreciprocal transport behaviors and first-principles density functional theory calculations. Our methodology paves the way for functional defect engineering that entangles spin and momentum of itinerant electrons for emerging electronic applications.

43. Topological magnon band crossing in Y2Ir2O7
Thi Huyen Nguyen, Jaeseok Son, Soyeun Kim, Hwanbeom Cho, Choong H. Kim, Y. P. Wang, Kenneth S. Burch, In-Sang Yang, Jaehong Jeong, Je-Geun Park, S.J. Moon, and T. W. Noh
Phys. Rev. Lett. 127, 257203 (23 Dec 2021)
Topological magnonic materials have attracted much interest because of the potential for dissipationless spintronic applications. Pyrochlore iridates are theoretically regarded as good candidates for designing topological magnon bands. However, experimental identification of topological magnon bands in pyrochlore iridates remains elusive. We explored this possibility in Y2Ir2O7 using Raman spectroscopy to measure both the single-magnon excitations and anomalous phonon shifts. From the single-magnon energies and tight-binding model calculations concerning the phonons, we determined the key parameters in the spin Hamiltonian. These confirm that Y2Ir2O7 hosts a nontrivial magnon band topology distinct from other pyrochlore iridate compounds. Our work demonstrates that pyrochlore iridates constitute a system in which the magnon band topology can be tailored and that Raman spectroscopy is a powerful technique to explore magnon band topology.
42. Observation of metallic electronic structure in a single-atomic-layer oxide
Byungmin Sohn, Jeong Rae Kim, Choong H. Kim, Sangmin Lee, Sungsoo Hahn, Soonsang Huh, Donghan Kim, Youngdo Kim, Wonshik Kyung, Minsoo Kim, Younsik Kim, Miyoung Kim, Tae Won Noh, and Changyoung Kim
Nat. Commun. 12, 6171 (26 Oct 2021) [arXiv:2109.11090]
Correlated electrons in transition metal oxides exhibit a variety of emergent phases. When transition metal oxides are confined to a single-atomic-layer thickness, experiments so far have shown that they usually lose diverse properties and become insulators. In an attempt to extend the range of electronic phases of the single-atomic-layer oxide, we search for a metallic phase in a monolayer-thick epitaxial SrRuO3 film. Combining atomic-scale epitaxy and angle-resolved photoemission measurements, we show that the monolayer SrRuO3 is a strongly correlated metal. Systematic investigation reveals that the interplay between dimensionality and electronic correlation makes the monolayer SrRuO3 an incoherent metal with orbital-selective correlation. Furthermore, the unique electronic phase of the monolayer SrRuO3 is found to be highly tunable, as charge modulation demonstrates an incoherent-to-coherent crossover of the two-dimensional metal. Our work emphasizes the potentially rich phases of single-atomic-layer oxides and provides a guide to the manipulation of their two-dimensional correlated electron systems.
41. Hund’s metallicity enhanced by van Hove singularity in cubic perovskite systems
Hyeong Jun Lee, Choong H. Kim*, and Ara Go* (*: correspondence)
Phys. Rev. B 104, 165138 (22 Oct 2021) [arXiv:2107.05906]
A van Hove singularity (VHS) often significantly amplifies the electronic instability of a crystalline solid, including correlation-induced phenomena such as Hund’s metallicity. We perform a systematic study on the interplay between Hund’s coupling and electronic structures with a VHS focusing on Hund’s metallicity. We construct a simplified tight-binding model targeting cubic perovskite materials and test the effects of the VHS utilizing dynamical mean-field theory with an exact diagonalization solver. The quasiparticle weight and the low-frequency power exponent of the self-energy provide a quantitative estimation of metallicity over the phase diagram. We find the VHS to substantially enhance Hund’s metallicity. The results here suggest a range of parameters through which a VHS can bring great synergy with Hund’s coupling.
40. Pressure-induced transition from Jeff=1/2 to S=1/2 states in CuAl2O4
Hwanbeom Cho, Choong H. Kim, Yongmoon Lee, Kazuki Komatsu, Byeong-Gwan Cho, Deok-Yong Cho, Taehun Kim, Chaebin Kim, Younghak Kim, Tae Yeong Koo, Yukio Noda, Hiroyuki Kagi, Daniel I. Khomskii, Donghoon Seoung, and Je-Geun Park
Phys. Rev. B Lett. 103, L081101 (3 Feb 2021) [arXiv:2101.00754]
The spin-orbit entangled (SOE) Jeff state has been a fertile ground to study quantum phenomena. Contrary to the conventional weakly correlated Jeff=1/2 state of 4d and 5d transition metal compounds, the ground state of CuAl2O4 hosts a Jeff=1/2 state with a strong correlation of Coulomb U. Here, we report that, surprisingly, Cu2+ ions of CuAl2O4 overcome the otherwise usually strong Jahn-Teller distortion and instead stabilize the SOE state, although the cuprate has relatively small spin-orbit coupling. From the x-ray absorption spectroscopy and high-pressure x-ray diffraction studies, we obtained definite evidence of the Jeff=1/2 state with a cubic lattice at ambient pressure. We also found the pressure-induced structural transition to a compressed tetragonal lattice consisting of the spin-only S=1/2 state for pressure Pc>8GPa. This phase transition from the Mott insulating Jeff=1/2 to the S=1/2states is a unique phenomenon. Our study offers an example of the SOE Jeff state under strong electron correlation and its pressure-induced transition to the S=1/2 state.
39. Electric field driven octahedral rotation in perovskite
Wonshik Kyung†, Choong H. Kim†, Yeong Kwan Kim, Beomyoung Kim, Chul Kim, Woobin Jung, Junyoung Kwon, Minsoo Kim, Aaron Bostwick, Jonathan D. Delinger, Yoshiyuki Yoshida, and Changyoung Kim (†: co-first)
npj Quantum Materials 6, 5 (8 Jan 2021) [arXiv:2012.14105]
Rotation of MO6 (M = transition metal) octahedra is a key determinant of the physical properties of perovskite materials. Therefore, tuning physical properties, one of the most important goals in condensed matter research, may be accomplished by controlling octahedral rotation (OR). In this study, it is demonstrated that OR can be driven by an electric field in Sr2RuO4. Rotated octahedra in the surface layer of Sr2RuO4 are restored to the unrotated bulk structure upon dosing the surface with K. Theoretical investigation shows that OR in Sr2RuO4 originates from the surface electric field, which can be tuned via the screening effect of the overlaid K layer. This work establishes not only that variation in the OR angle can be induced by an electric field, but also provides a way to control OR, which is an important step toward in situ control of the physical properties of perovskite oxides.

38. Interplay between spin-orbit coupling and van Hove singularity in the Hund's metallicity of Sr2RuO4
Hyeong Jun Lee, Choong H. Kim*, and Ara Go* (*: correspondence)
Phys. Rev. B 102, 195115 (10 Nov 2020) [arXiv:2002.04825]
We investigate the roles of spin-orbit coupling and the Van Hove singularity in the dynamical properties of Sr2RuO4, which become prominent at zero and very low temperature, by means of density functional theory plus dynamical mean-field theory with an exact diagonalization solver. We examine the crossover between a Fermi liquid and a Hund's metal for a wide range of temperatures and Hund's coupling. In the absence of doping, we confirm that the Fermi liquid persists at zero temperature even with nonzero Hund's coupling. The freezing-moment mechanism suggests that thermal fluctuations lead to a suppression of the Fermi liquid phase and promote Hund's metallicity with incoherence. We show that the Van Hove singularity is an additional key ingredient to drive the suppression at very low temperature by observing a doping dependence of the freezing or long-lived paramagnetic moments. The role of spin-orbit coupling is marked by an amplified Van Vleck contribution of spin susceptibility, significantly promoting Hund's metallicity. Together with the known doping dependence of Hund's metallicity, the additional Van Hove singularity doping dependence found here may allow for the control of the Hund's metallicity of Sr2RuO4(t42g) by a fine tuning of the doping or possibly even strain.
37. Spin-orbit coupling effects on spin-phonon coupling in Cd2Os2O7
Taehun Kim, Choong H. Kim, Jaehong Jeong, Pyeongjae Park, Kisoo Park, Ki Hoon Lee, J. C. Leiner, D. Ishikawa, A. Q. R. Baron, Zenji Hiroi, and Je-Geun Park
Phys. Rev. B Rapid Comm. 102, 201101(R) (3 Nov 2020) [arXiv:2010.10684]

36. Evidence of structural evolution in Sr2RhO4 studied by time-resolved optical reflectivitiy spectroscopy
Min-Cheol Lee, Inho Kwak, Choong H. Kim, Bumjoo Lee, B. C. Park, J. Kwon, Wonsik Kyung, Changyoung Kim, Tae Won Noh, and Kyungwan Kim
Phys. Rev. B 100, 235139 (24 Dec 2019)
35. Ultrafast dynamics in the Lifshitz-type 5d pyrochlore antiferromagnet Cd2Os2O7
Inho Kwak, Min-Cheol Lee, Byung Cheol Park, Choong H. Kim, Bumjoo Lee, C.W. Seo, J. Yamamura, Z. Hiroi, T.W. Noh, and K.W. Kim
Phys. Rev. B 100, 144309 (25 Oct 2019)
34. Theoretical evidence of spin-orbital-entangled Jeff = 1/2 state in the 3d transition metal oxide CuAl2O4
Choong H. Kim*, Santu Baidya, Hwanbeom Cho, V. V. Gapontsev, S. V. Streltsov, Daniel I. Khomskii, Je-Geun Park, Ara Go*, and Hosub Jin* (*: correspondence)
Phys. Rev. B Rapid Comm. 100, 161104(R) (4 Oct 2019) [arXiv:1810.08594]
33. Chern insulator with a nearly flat band in the metal-organic-framework-based Kagome lattice
Santu Baidya, Seungjin Kang, Choong H. Kim*, and Jaejun Yu* (*: correspondence)
Sci. Rep. 9, 13807 (24 Sep 2019)
32. Two-dimensional Peierls instability via zone boundary Dirac line nodes in layered perovskite oxides
Jin-Hong Park, Seung Hun Lee, Choong H. Kim, Hosub Jin, and Bohm-Jung Yang
Phys. Rev. B 99, 195107 (6 May 2019) [arXiv:1808.06830]
31. Unconventional spin-phonon coupling via the Dzyaloshinskii-Moriya interaction
Jaeseok Son, Byung Cheol Park, Choong H. Kim, Hwanbeom Cho, So Yeun Kim, Luke J. Sandilands, Changhee Sohn, Je-Geun Park, Soon Jae Moon, and Tae Won Noh
npj Quantum Materials 4, 17 (29 Apr 2019)
30. Strong spin-phonon coupling unveiled by coherent phonon oscillations in Ca2RuO4
Min-Cheol Lee, Choong H. Kim, Inho Kwak, C. W. Seo, Changhee Sohn, F. Nakamura, C. Sow, Y. Maeno, E.-A. Kim, T. W. Noh, and K. W. Kim
Phys. Rev. B 99, 144306 (15 Apr 2019) [arXiv:1712.03088]
29. Crystalline topological Dirac semimetal phase in rutile structure β'-PtO2
Rokyeon Kim*, Bohm-Jung Yang, and Choong H. Kim* (*: correspondence)
Phys. Rev. B 99, 045130 (16 Jan 2019) [arXiv:1809.08963]
28. Orbital-selective confinement effect of Ru 4d orbitals in SrRuO3 ultrathin film
Soonmin Kang, Yi Tseung, Beom Hyun Kim, Seokhwan Yun, Byungmin Sohn, Bongju Kim, Daniel McNally, Eugenio Paris, Choong H. Kim, Changyoung Kim, Tae Won Noh, Sumio Ishihara, Thorsten Schmitt, and Je-Geun Park
Phys. Rev. B 99, 045113 (7 Jan 2019) [arXiv:1812.09844]

27. Tunable magnetic topological insulating phases in monolayer CrI3
Santu Baidya*, Jaejun Yu*, and Choong H. Kim* (*: correspondence)
Phys. Rev. B 98, 155148 (30 Oct 2018)
26. Engineering carrier effective masses in ultrathin quantum wells of IrO2
Jason K. Kawasaki, Choong H. Kim, Jocienne N. Nelson, Sophie Crisp, Christian J. Zollner, Eric BiegenWald, John T. Heron, Craig J. Fennie, Darrell G. Schlom, and Kyle M. Shen
Phys. Rev. Lett. 121, 176802 (25 Oct 2018)
25. Abnormal phase flip in the coherent phonon oscillations of Ca2RuO4
Min-Cheol Lee, Choong H. Kim, Inho Kwak, J. Kim, S. Yoon, Byung Cheol Park, Bumjoo Lee, F. Nakamura, C. Sow, Y. Maeno, T. W. Noh, and K. W. Kim
Phys. Rev. B 98, 161115(R) (17 Oct 2018) [arXiv:1808.06026]

24. Topological superconductivity in metal/quantum-spin-ice heterostructures
Jian-Huang She, Choong H. Kim, Craig J. Fennie, Michael Lawler, and Eun-Ah Kim
npj Quantum Materials 2, 64 (20 Nov 2017) [arXiv:1603.02692]
23. Electronic reconstruction enhanced tunneling conductance at terrace edges of ultrathin oxide films
Lingfei Wang, Rokyeon Kim, Yoonkoo Kim, Choong H. Kim, Sangwoon Hwang, Myung Rae Cho, Yeong Jae Shin, Saikat Das, Jeong Rae Kim, Sergei V. Kalinin, Miyoung Kim, Sang Mo Yang, and Tae Won Noh
Advanced Materials 29, 1702001 (12 Oct 2017) [arXiv:1711.04622]
22. Two-magnon scattering in 5d all-in/all-out pyrochlore magnet Cd2Os2O7
Thi Minh Hien Nguyen, Luke J. Sandilands, C.H. Sohn, C. H. Kim, A. L. Wysocki, In-Sang Yang, S.J. Moon, Jae-Hyeon Ko, J. Yamaura, Z. Hiroi, and Tae Won Noh
Nat. Commun. 8, 251 (15 Aug 2017)
21. Properties of spin-1/2 triangular-lattice antiferromagnets CuY2Ge2O8 and CuLa2Ge2O8
Hwanbeom Cho, Marie Kratochvílová, Hasung Sim, Ki-Young Choi, Choong Hyun Kim, Carley Paulsen, Maxim Avdeev, Darren C. Peets, Younghun Jo, Sanghyun Lee, Yukio Noda, Michael J. Lawler, and Je-Geun Park
Phys. Rev. B 95, 144404 (5 Apr 2017) [arXiv:1703.04252]
20. Photon energy dependent circular dichroism in angle-resolved photoemission from Au(111) surface states
Hanyoung Ryu, Inkyung Song, Beomyoung Kim, Soohyun Cho, Shoresh Soltani, Timur Kim, Moritz Hoesch, Choong H. Kim, and Changyoung Kim
Phys. Rev. B 95, 115144 (24 March 2017)
19. Strong spin-phonon coupling mediated by single ion anisotropy in the all-in--all-out pyrochlore magnet Cd2Os2O7
C. H. Sohn, C. H. Kim, L. J. Sandilands, N. T. M. Hien, S. Y. Kim, H. J. Park, K. W. Kim, S. J. Moon, J. Yamaura, Z. Hiroi, and T. W. Noh
Phys. Rev. Lett. 118, 117201 (13 Mar 2017)

18. Electronic structure of the Kitaev material α-RuCl3 probed by photoemission and inverse photoemission spectroscopies
Soobin Sinn, Choong Hyun Kim, Beom Hyun Kim, Kyung Dong Lee, Choong Jae Won, Ji Seop Oh, Moonsup Han, Young Jun Chang, Namjung Hur, Hitoshi Sato, Byeong-Gyu Park, Changyoung Kim, Hyeong-Do Kim, and Tae Won Noh
Sci. Rep. 6, 39544 (21 Dec 2016) [arXiv:1608.06066]
17. Manipulation of electronic structure via alteration of local orbital environment in [(SrIrO3)m,(SrTiO3)](m=1, 2, and ∞) superlattices
So Yeun Kim, Choong H. Kim, L. J. Sandilands, C. H. Sohn, J. Matsuno, H. Takagi, K. W. Kim, Y. S. Lee, S. J. Moon, and T. W. Noh
Phys. Rev. B 94, 245113 (6 Dec 2016)
16. Spin-orbit coupling induced band structure change and orbital character of epitaxial IrO2 film
Woo Jin Kim, So Yeun Kim, Choong H. Kim, Chang Hee Sohn, O. B. Korneta, Seung Chul Chae, and Tae Won Noh
Phys. Rev. B 93, 045104 (6 Jan 2016)

15. Hierarchical spin-orbital polarization of a giant Rashba system
Lewis Bawden, Jonathan M. Riley, Choong H. Kim, Raman Sankar, Eric J. Monkman, Daniel E. Shai, Haofei I. Wei, Edward B. Lochocki, Justin W. Wells, Worawat Meevasana, Timur K. Kim, Moritz Hoesch, Yoshiyuki Ohtsubo, Patrick Le Fèvre, Craig J. Fennie, Kyle M. Shen, Fangcheng Chou, and Phil D.C. King
Science Advances 1, e1500495 (25 Sep 2015) [arXiv:1507.08588]
14. Interplay of spin-orbit interactions, dimensionality, and octahedral rotations in semimetallic SrIrO3
Y. F. Nie, P. D. C. King, C. H. Kim, M. Uchida, H. I. Wei, B. D. Faeth, J. P. Ruf, J. P. C. Ruff, L. Xie, X. Pan, C. J. Fennie, D. G. Schlom, and K. M. Shen
Phys. Rev. Lett. 114, 016401 (6 Jan 2015) [arXiv:1501.02265]
13. Correlated versus conventional insulating behavior in the Jeff=1/2 vs. 3/2 bands in the layered iridate Ba2IrO4
M. Uchida, Y. F. Nie, P. D. C. King, C. H. Kim, C. J. Fennie, D. G. Schlom, and K. M. Shen
Phys. Rev. B 90, 075142 (25 Aug 2014) [arXiv:1408.6314]
12. Temperature evolution of itinerant ferromagnetism in SrRuO3 probed by optical spectroscopy
D. W. Jeong, Hong Chul Choi, Choong H. Kim, Seo Hyoung Chang, C. H. Sohn, H. J. Park, T. D. Kang, Deok-Yong Cho, S. H. Baek, C. B. Eom, J. H. Shim, J. Yu, K. W. Kim, S. J. Moon, and T. W. Noh
Phys. Rev. Lett. 110, 247202 (11 Jun 2013)
11. Strain-induced topological insulator phase and effective magnetic interactions in Li2IrO3
Heung-Sik Kim, Choong H. Kim, Hogyun Jeong, Hosub Jin, and Jaejun Yu
Phys. Rev. B 87, 165117(R) (11 Apr 2013)
10. Orbital chirality and Rashba interaction in magnetic bands
Jin-Hong Park, Choong H. Kim, Hyun-Woo Lee, and Jung Hoon Han
Phys. Rev. B 87, 041301(R) (3 May 2013) [arXiv:1207.0089]
09. Spin and orbital angular momentum structure of Cu(111) and Au(111) surface states
Beomyoung Kim, Choong H. Kim, Panjin Kim, Wonsig Jung, Yeongkwan Kim, Yoonyoung Koh, Masashi Arita, Kenya Shimada, Hirofumi Namatame, Masaki Taniguchi, Jaejun Yu, and Changyoung Kim
Phys. Rev. B 85, 195402 (2 May 2012) [arXiv:1112.2469]
08. Orbital Rashba effect and its detection by circular dichroism angle-resolved photoemission spectroscopy
Jin-Hong Park, Choong H. Kim, Jun Won Rhim, and Jung Hoon Han
Phys. Rev. B 85, 195401 (2 May 2012)
07. Topological quantum phase transition in transition metal oxide Na2IrO3
Choong H. Kim, Heung Sik Kim, Hogyun Jeong, Hosub Jin, and Jaejun Yu
Phys. Rev. Lett. 108, 106401 (5 Mar 2012) [arXiv:1201.5929]
06. Topological quantum phase transitions driven by external electric fields in Sb2Te3 thin films
Minsung Kim, Choong H. Kim, Heungsik Kim, and Jisoon Ihm
Proc. Natl. Acad. Sci. 109, 671 (27 Dec 2011)
05. Orbital-angular-momentum based origin of Rashba-type surface band splitting
Seung Ryong Park, Choong H. Kim, Jaejun Yu, Jung Hoon Han, and Changyoung Kim
Phys. Rev. Lett. 107, 156803 (6 Oct 2011) [arXiv:1107.1554]
04. Electronic structure of double perovskite A2FeReO6(A=Ba and Ca): interplay between spin-orbit interaction, electron correlation, and lattice distortion
B.C. Jeon, Choong H. Kim, S.J. Moon, Woo Seok Choi, Hogyun Jeong, Y.S. Lee, J. Yu, C.J. Won, J.H. Jung, N. Hur, and T.W. Noh
J. Phys.: Condens. Matter 22, 345602 (2 Aug 2010)
03. Fundamental thickness limit of itinerant ferromagnetic SrRuO3 thin films
Young Jun Chang, Choong H. Kim, S.-H. Phark, Y.S. Kim, J. Yu, and T.W. Noh
Phys. Rev. Lett. 103, 057201 (30 Jul 2009) [arXiv:0903.0225]
02. A spin-dependent local moment approach to the Anderson impurity model
Choong H. Kim, and Jaejun Yu
J. Phys.: Condens. Matter 19, 456203 (11 Oct 2007) [arXiv:0709.1187v2]
01. Interplay between local electron correlation and Jahn-Teller electron-phonon interaction
Choong H. Kim, and Hyun C. Lee
Phys. Rev. B 73, 113109 (16 Mar 2006) [arXiv:cond-mat/0603449v1]