- 2003 Ph. D. in Physics at University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- 1996 M. S. in Physics at Sungkyunkwan University, Suwon, Korea
- 1994 B. A. in Physics at Sungkyunkwan University, Suwon, Korea
|◆ Employment and Professional Experience
- 2013- Director, Center for Quantum Materials & Superconductivity, Sungkyunkwan University, Korea (ROK)
- 2018- Professor, Department of Physics, Sungkyunkwan University, Korea (ROK)
- 2012-2018 Associate Professor, Department of Physics, Sungkyunkwan University, Korea (ROK)
- 2008-2012 Assistant Professor, Department of Physics, Sungkyunkwan University, Korea (ROK)
- 2005-2008 J. Robert Oppenheimer(JRO) Fellow, Los Alamos National Laboratory, USA
- 2003-2005 Postdoctoral Research Associate, Los Alamos National Laboratory, USA
- 1998-2003 Research Assistant, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- 1997-1998 Teaching Assistant, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- 1994-1996 Teaching Assistant, Sungkyunkwan University, Suwon, Korea (ROK)
|◆ Awards and honors
- 2011 SKKU Young Fellow, Sungkyunkwan University, Suwon, Korea (ROK)
- 2010 POSCO Science Fellow, POSCO TJ Park Science Foundation,Seoul, Korea (ROK)
- 2007 Postdoctoral Distinguished Performance Award, Los Alamos National Laboratory
- 2007 Outstanding Young Research Award, Association of Korean Physicists in America
- 1997 Rotary international scholar, Korea (ROK)
|◆ Professional Activities
- 2008-present member of Korean Physical Society
- 2000-present member of American Physical Society
- 2008-present member of Korean Superconductivity Society
- 2006-present referee for Physical Review
|◆ Selected Publications
- Textured electronic state in the heavy fermion CeRhIn5, Phys. Rev. Lett. 108, 077003 (2012.02).
- Isotropic quantum scattering and unconventional superconductivity, Nature 456, 366 (2008. 11).
- Probing the nodal gap in the pressure-induced heavy fermion superconductor CeRhIn5, Phys. Rev. Lett. 101, 177002 (2008. 10).
- Electronic duality in strongly correlated matter, Proc. Nat. Acad. Sci. 105, 6825 (2008).
- Hidden magnetism and quantum criticality in the heavy fermion superconductor CeRhIn5, Nature 440, 65 (2006).
- Reversible tuning of the heavy-fermion ground state in CeCoIn5, Phys. Rev. Lett. 97, 056404 (2006).
- Anomalous Pressure Dependence of Kadowaki-Woods ratio and crystal field effects in mixed-valence YbInCu4, Phys. Rev. Lett. 96, 046405 (2006).
- A novel dielectric anomaly in cuprates and nickelates: signature of an electronic glassy state, Phys. Rev. Lett. 94, 017002 (2005).
- Evidence for the coexistence of anisotropic superconducting gap and nonlocal effects in the non-magnetic superconductor LuNi2B2C, Phys. Rev. Lett. 92, 237002 (2004).
- Direct observation of nodal quasiparticles in an unconventional superconductor: field-angle dependent heat capacity of YNi2B2C, Phys. Rev. Lett. 90, 177001 (2003).
|◆ Research Interests and Highlights
General Interests: My research interests center on discovering and studying new quantum phases emerging near T=0 K in strongly correlated systems. These phases, such as unconventional superconductivity, unusual weak ferromagnetism, electronic ferroelectricity, etc. are unexpected from conventional theories of quantum phase transitions and often are incompletely described by model Hamiltonians. Subjecting multifunctional materials, mixed-valence materials, heavy fermion compounds and strongly correlated superconductors to pressure and magnetic (electric) field allows the exploration of the new phases using variety of experimental techniques, including specific heat, Hall effect, dielectric constant, electrical resistivity, magnetic susceptibility, and neutron scattering.
Highlights of Past Research: My Ph.D. thesis research, carried out under the supervision of Dr. Myron. B. Salamon at University of Illinois at Urbana-Champaign, explored anisotropic superconducting gap structures of unconventional superconductors in which gap zeroes (or nodes) exist on the Fermi surface. Unlike gapless superconductivity, which can occur in conventional superconductors, the Fermi momenta of quasiparticles at nodes are restricted to nodal regions of the Fermi surface, giving a strong directional dependence to various physical properties. Using field-directional specific heat measurements, where magnetic field direction was rotated while other parameters were held constant, we demonstrated for the first time that the electronic density of states modulate as a function of magnetic field angle, reflecting the anisotropic gap structure of unconventional superconductors. After our seminal work, this technique has been popularly used to probe the superconducting gap nature.
My postdoctoral work, performed at Los Alamos National Laboratory under the guidance of Dr. Joe D. Thompson, focused on exploring and understanding new quantum phases in strongly correlated systems that emerge near T=0 K. Measurements of the electric and magnetic response of hole-doped insulators La2Cu1-xLixO4 and La2-xSrxNiO4 revealed a novel electronic glassy state and its correlation with a magnetic glassy state. In the pressure-induced heavy fermion superconductor CeRhIn5, we identified magnetic field-induced antiferromagnetic (AFM) order deep in the superconducting (SC) state. The critical field required to induce a quantum phase transition between pure SC and coexisting SC+AFM phases increased with increasing pressure, suggesting AFM as a broken symmetry that competes with unconventional superconductivity. In classes of unconventional superconductors, including high-Tc cuprates, anomalous behaviors (or non-Fermi liquid behaviors) in the normal state have been associated with projected quantum critical points (QCPs) inside superconducting dome, but identification of the QCPs has been elusive. By locating and exploring the QCPs in a model unconventional superconductor CeRhIn5, we demonstrated how magnetic fluctuations are responsible for anomalous normal state behaviors and interplay with unconventional superconductivity.