Sang-Wook Cheong
· Distinguished Professor Henry Rutgers Professor Board of Governors Professor Director, Center for Quantum Materials Synthesis Member of the Graduate FacultyRutgers University · Physics and Astronomy
Active 2014–2024
About
Sang-Wook Cheong is a Distinguished Professor, Henry Rutgers Professor, and Board of Governors Professor at Rutgers University, where he is also the Director of the Center for Quantum Materials Synthesis. His research focuses on the synthesis and study of a large variety of compounds, including oxides and intermetallics, with interesting structural instabilities and unconventional electronic and magnetic ground states. He is particularly interested in multiferroic materials, which exhibit two or more ferroic orders simultaneously, such as ferromagnetism, ferroelectricity, and ferroelasticity. His investigations employ various imaging techniques, including atomic force microscopy, piezoresponse force microscopy, transmission electron microscopy, scanning tunneling microscopy, neutron scattering, and x-ray diffraction. Cheong's work involves growing a broad range of samples through methods such as solid state reaction, chemical vapor transport, chemical solution methods, high-temperature flux, optical floating zone, high-pressure synthesis, and pulsed laser deposition, from polycrystals to single crystals and thin films.
Research topics
- Physics
- Condensed matter physics
- Materials science
- Artificial Intelligence
- Nanotechnology
- Computer Science
- Optoelectronics
- Quantum mechanics
- Optics
Selected publications
Permutable SOS (symmetry operational similarity)
npj Quantum Materials · 2021 · 49 citations
- Computer Science
- Artificial Intelligence
- Physics
Abstract Based on symmetry consideration, quasi-one-dimensional (1D) objects, relevant to numerous observables or phenomena, can be classified into eight different types. We provide various examples of each 1D type and discuss their symmetry operational similarity (SOS) relationships, which are often permutable. A number of recent experimental observations, including current-induced magnetization in polar or chiral conductors, non-linear Hall effect in polar conductors, spin-polarization of tunneling current to chiral conductors, and ferro-rotational domain imaging with linear gyration are discussed in terms of (permutable) SOS. In addition, based on (permutable) SOS, we predict a large number of new phenomena in low symmetry materials that can be experimentally verified in the future.
Ambient effect on the Curie temperatures and magnetic domains in metallic two-dimensional magnets
npj 2D Materials and Applications · 2021 · 26 citations
- Condensed matter physics
- Materials science
- Nanotechnology
Abstract The emergent magnetic two-dimensional (2D) materials provide ideal solid-state platforms for a broad range of applications including miniaturized spintronics, nonreciprocal optics, and magnetoelectric sensors. Owing to the general environmental sensitivity of 2D magnets, the understanding of ambient effects on 2D magnetism is critical. Apparently, the nature of itinerant ferromagnetism potentially makes metallic 2D magnets insensitive to environmental disturbance. Nevertheless, our systematic study showed that the Curie temperature of metallic 2D Fe 3 GeTe 2 decreases dramatically in the air but thick Fe 3 GeTe 2 exhibits self-protection. Remarkably, we found the air exposure effectively promotes the formation of multiple magnetic domains in 2D Fe 3 GeTe 2 , but not in bulk Fe 3 GeTe 2 . Our first-principles calculations support the scenario that substrate-induced roughness and tellurium vacancies boost the interaction of 2D Fe 3 GeTe 2 with the air. Our elucidation of the thickness-dependent air-catalyzed evolution of Curie temperatures and magnetic domains in 2D magnets provides critical insights for chemically decorating and manipulating 2D magnets.
Seeing is believing: visualization of antiferromagnetic domains
npj Quantum Materials · 2020 · 107 citations
1st authorCorresponding- Computer Science
- Nanotechnology
- Artificial Intelligence
Abstract Understanding and utilizing novel antiferromagnetic (AFM) materials has been recently one of the central issues in condensed matter physics, as well as in materials science and engineering. The relevant contemporary topics include multiferroicity, topological magnetism and AFM spintronics. The ability to image magnetic domains in AFM materials is of key importance for the success of these exciting fields. While imaging techniques of magnetic domains on the surfaces of ferro-(ferri)magnetic materials with, for example, magneto-optical Kerr microscopy and magnetic force microscopy have been available for a number of decades, AFM domain imaging is a relatively new development. We review various experimental techniques utilizing scanning, optical, and synchrotron X-ray probes to visualize AFM domains and domain walls, and to unveil their physical properties. We also discuss the existing challenges and opportunities in these techniques, especially with further increase of spatial and temporal resolution.
Physical Review Letters · 2020 · 95 citations
- Materials science
- Condensed matter physics
- Physics
Hafnia (HfO_{2})-based thin films have promising applications in nanoscale electronic devices due to their robust ferroelectricity and integration with silicon. Identifying and stabilizing the ferroelectric phases of HfO_{2} have attracted intensive research interest in recent years. In this work, first-principles calculations on (111)-oriented HfO_{2} are used to discover that imposing an in-plane shear strain on the metastable tetragonal phase drives it to a polar phase. This in-plane-shear-induced polar phase is shown to be an epitaxial-strain-induced distortion of a previously proposed metastable ferroelectric Pnm2_{1} phase of HfO_{2}. This ferroelectric Pnm2_{1} phase can account for the recently observed ferroelectricity in (111)-oriented HfO_{2}-based thin films on a SrTiO_{3} (STO) (001) substrate [Nat. Mater. 17, 1095 (2018)NMAACR1476-112210.1038/s41563-018-0196-0]. Further investigation of this alternative ferroelectric phase of HfO_{2} could potentially improve the performances of HfO_{2}-based films in logic and memory devices.
Frequent coauthors
- 9 shared
Jae‐Wook Kim
Korea Institute of Machinery and Materials
- 9 shared
Choongjae Won
Pohang University of Science and Technology
- 8 shared
Han Woong Yeom
- 7 shared
Xianghan Xu
Princeton University
- 7 shared
Lunyong Zhang
Harbin Institute of Technology
- 6 shared
William Ratcliff
- 6 shared
Markus Bleuel
NIST Center for Neutron Research
- 4 shared
Hae‐Young Kee
Awards & honors
- 2010 James C. McGroddy Prize for New Materials
- Korean Academy of Science and Technology (KAST) Fellow (2015…
- Highly Cited Researchers list by Thomson Reuters (2016)
- 2018 Clarivate Analytics Highly Cited Researchers list
- American Physical Society Outstanding Referee recognition
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