Seunghyun Khim


Department of Physics and Astronomy
Seoul National University
599 Gwanak-ro, Gwanak-gu
Seoul 151-747, Korea

 skhim@phya.snu.ac.kr
+82-2-888-0768 (office)
+82-2-888-0769 (fax)

 

Education

Seoul National University     Physics         B.S.                   3 / 2001    2 / 2007

Seoul National University     Physics         Ph.D.                 3 / 2007    2 / 2013

Thesis subject: Crystal Growth and Upper Critical Field Properties of Iron-based Superconductors and a Chalcogenide Superconductor

 

Awards

Hi Seoul Science Fellowship from Seoul Scholarship Foundation
(3 / 2009 – 2 / 2010)

Best post awards in Korean Physics Society Fall Meeting (2009)

BK21 (Brain Korea 21) scholarship (3 / 2010 – 8 / 2010, 9 / 2011 - 2 / 2012)

 

Research Topic

I have grown single crystals of iron-based superconductors and chalcogenide compounds containing 4d / 5d transition metals and found 5.5 K superconductivity in a quasi-one-dimensional structure Nb2PdxSe5. I have studied high magnetic field properties of iron-based superconductors and found that the Pauli limiting effect played an important role in determining the upper critical field. In the new Nb2PdxSe5 superconductor, the upper critical field along the conducting chain direction found to reach up to 35 T exceeding the Pauli limiting field due to its low dimensional structure and spin-orbit coupling effect.

 

Experience

2013

l  Exploring chalcogenide compounds with 4d/5d transition metals.

 

2012

l  Synthesis a new chalcogenide superconductor Nb2PdxSe5 (5.5 K) and Nb3PdxSe7 (2 K)

l  Neutron scattering experiment in High Resolution Powder Diffractometer (HRPD) in Hanaro reactor, Korea Atomic Energy Research Institute (KAERI)

l  National High Magnetic Field Laboratory (NHMFL) DC magnet (Tallahassee, Florida) experiment: Feb. 2-6 and Jun. 11-15

 

2011

l  Making a specific heat measurement probe for high field experiment

l  NHMFL DC magnet experiments: Jan. 3-7, May 21-25, Sep. 26-30 and Dec 19-23

l  Study upper critical field properties of LiFeAs and Sr(Fe,Ni)2As2 single crystals

 

2010

l  Synthesis LiFeAs, Fe(Se,Te) and Sr(Fe,Ni)2As2 , Bi2(Se,Te)3 single crystals

l  NHMFL DC magnet experiments:  Feb. 22-26 and Jul. 19-23

l  Study upper critical field properties of Fe(Se,Te) and Ba(Fe,Ru)2As2 single crystals

 

2009

l  Synthesis A(Fe,M)2As2 (A = Eu, Ca, Sr, M = Co, Mn) single crystals

l  NHMFL DC magnet experiments: April 6-10

l  NHMFL pulsed field experiment (Los Alamos, New Mexico): Apr. 13-19

l  Study upper critical field properties of the Sr(Fe,Co)2As2 single crystals

l  Participate in the NHMFL summer school 2009

 

2008

l  Synthesis lead-free multiferroic composite materials.

l  Synthesis a single crystalline (Ba,K)Fe2As2 superconductor.

l  NHMFL DC magnet experiment:  Sep. 22-26

 

 

Experimetal
Skills

l  Synthesizing solid state materials with the solid state reaction, flux method, chemical vapor transport and arc melting technique

l  Powder and capillary spinner diffraction experiment in High Resolution X-Ray Diffractometer

l  Structure analysis with the Rietveld refinement using Fullprof software

l  Transport, torque and magnetocaloric effect measurements in the NHMFL (National High Magnetic Field Laboratory, USA)

l  Operation and maintenance of the Physical Property Measurement System (Quantum Design)

l  Operating customized piston-type pressure cells (< 2.5 GPa)

l  Programing Labview based software

 

Publication List

1. Hyeong-Jin Kim, Y. Liu, Yoon-Seok Oh, Seunghyun Khim, Ingyu Kim, G. Stewart, and Kee Hoon Kim, "Vortex-glass phase transition and superconductivity in an under-doped (Ba,K)Fe2As2 single crystal", Phys. Rev. B 79, 014514 (2009).

2. Jun Sung Kim, Seunghyun Khim, Liqin Yan, N. Manivannan, Yong Liu, Ingyu Kim, G. R. Stewart, and Kee Hoon Kim, "Evidence for Coexistence of Superconductivity and Magnetism in Single Crystals of Co-doped SrFe2As2", J. Phys.: Condens. Matter 21, 102203 (2009).

3. E. Dengler, J. Deisenhofer, H.-A. Krug von Nidda, Seunghyun Khim, J. S. Kim, Kee Hoon Kim, F. Casper, and A. Loidl, "Strong reduction of the Korringa relaxation in the spin-density wave regime of EuFe2As2 observed by electron spin resonance", Phys. Rev. B 81, 024406 (2010).

4. Seunghyun Khim, Jun Sung Kim, Jae Wook Kim, Suk Ho Lee, F. F. Balakirev, Yunkyu Bang, Kee Hoon Kim, "Nearly isotropic upper critical fields in a SrFe1.85Co0.15As2 single crystal", Physica C 470, S317 (2010) (Proceedings of the 9th International Conference on Materials and Mechanisms of Superconductivity).

5. Seunghyun Khim, Jae Wook Kim, Eun Sang Choi, Yunkyu Bang, Minoru Nohara, Hidenori Takagi, and Kee Hoon Kim, "Evidence for dominant Pauli paramagnetic effect in the upper critical field of single-crystalline FeTe0.6Se0.4", Phys. Rev. B 81, 184511 (2010).

6. S.J. Moon, J.H. Shin, D. Parker, W.S. Choi, I.I. Mazin, Y.S. Lee, J.Y. Kim, B.K. Cho, S.H. Khim, J.S. Kim, K.H. Kim, and T.W. Noh, "Dual character of magnetism in EuFe2As2: Optical spectroscopic and density-functional calculation study", Phys. Rev. B 81, 205114 (2010).

7. J. S. Kim, Seunghyun Khim, H. J. Kim, M. J. Eom, J. M. Law, R. K. Kremer, Ji Hoon Shim, and Kee Hoon Kim, "Electron-hole asymmetry in Co- and Mn-doped SrFe2As2",Phys. Rev. B 82, 024510 (2010).

8. Bumsung Lee, Seunghyun Khim, Jung Soo Kim, G. R. Stewart, and Kee Hoon Kim, "Single crystal growth and superconducting properties of LiFeAs", Europhysics Letters 91, 67002 (2010).

9. Yeongkwan Kim, Hyungju Oh, Chul Kim, Dongjoon Song, Wonsig Jung, Beomyoung Kim, Hyoung Joon Choi, Changyoung Kim, Bumsung Lee, Seunghyun Khim, Hyungjoon Kim, Keehoon Kim, Jongbeom Hong, and Yongseung Kwon, "Electronic structure of detwinned BaFe2As2 from photoemission and first principles", Phys. Rev. B 83, 064509 (2011).

10. Jewook Park, Seunghyun Khim, Gun Sang Jeon, Jun Sung Kim, Kee Hoon Kim and K. Char, "Observation of two-gap superconductivity in SrFe1.85Co0.15As2 single crystals by scanning tunneling microscopy and spectroscopy", New Journal of Physics 13, 033005 (2011).

11. Seunghyun Khim, Bumsung Lee, Jae Wook Kim, Eun Sang Choi, G. R. Stewart and Kee Hoon Kim, "Pauli-limiting effects in the upper critical fields of a clean LiFeAs single crystal", Phys. Rev. B 84, 104502 (2011).

12. Plengchart Prommapan, Makariy A. Tanatar, Bumsung Lee, Seunghyun Khim, Kee Hoon Kim, Ruslan Prozorov, "Magnetic field - dependent Labusch parameter in LiFeAs superconductor from Campbell penetration depth", Phys. Rev. B 84, 060509 (2011).

13. H. Gretarsson, A. Lupascu, Jungho Kim, D. Casa, T. Gog, W. Wu, S. R. Julian, Z. J. Xu, J. S. Wen, G. D. Gu, R. H. Yuan, Z. G. Chen, N.-L. Wang, S. Khim, K. H. Kim, M. Ishikado, I. Jarrige, S. Shamoto, J.-H. Chu, I. R. Fisher, Young-June Kim, "Revealing the dual nature of magnetism in iron pnictides and iron chalcogenides using x-ray emission

spectroscopy", Phys. Rev. B 84, 100509(R) (2011).

14. Xiaohang Zhang, Bumsung Lee, Seunghyun Khim, Kee Hoon Kim, Richard L. Greene and Ichiro Takeuchi, "Probing the order parameter of superconducting LiFeAs using Pb/LiFeAs and Au/LiFeAs point-contact spectroscopy", Phys. Rev. B 85, 094521 (2012).

15. Geunsik Lee, Hyo Seok Ji, Yeongkwan Kim, Changyoung Kim, Kristjan Haule, Gabriel Kotliar, Bumsung Lee, Seunghyun Khim, Kee Hoon Kim, Kwang S. Kim, Ki-Seok Kim, and Ji Hoon Shim, “Orbital Selective Fermi Surface Shifts and Mechanism of High Tc Superconductivity in Correlated AFeAs (A = Li, Na)”, Phys. Rev. Lett. 86, 165205 (2012).

 

Presentation (selected)

2008

Korean Physics Society Fall Meeting, “Growth of Single Crystals of (Ba,K)Fe2As2 / SrFe2As2”(Best Poster Awards)

 

2009

1. M2S-IX in Tokyo, “Isotropic upper critical field Hc2 in a FeSe0.4Te0.6 single crystal” (Poster)

2. APCTP 2009 Winter Workshop on Frontiers in Electronic Quantum Matter, “Hole- and Electron- Doping Effects on Single Crystals of SrFe2As2” (Poster)

3. Korean Physics Society Fall Meeting, “Upper critical fields Hc2 in Co-doped SrFe2As2 and Fe(Se,Te) single crystals” (Oral)

 

2010

1. APS March Meeting in Portland, “Evidence for dominant Pauli paramagnetic effect in the upper critical fields of a FeSe0.4Te0.6 superconductor” (Oral)

2. APCTP-A3 Winter School and Workshop on Frontiers in Electronic Quantum Matter, “Evidence for dominant Pauli paramagnetic effect in the upper critical fields of a FeTe0.6Se0.4 superconductor” (Poster)

3. 10th Japan-Korea-Taiwan Symposium on Strongly Correlated Electron Systems, “Evidence for dominant Pauli paramagnetic effect in the upper critical fields of a FeTe0.6Se0.4 superconductor” (Poster)

4. The Korea Institute of Applied Superconductivity and Cryogenics 2010, “The Upper Critical Field (Hc2) Study on Fe-based High-TC Superconductors” (Oral)

 

2011

1. APS March Meeting in Dallas, “Upper critical field study of a LiFeAs single crystal grown by Sn flux” (Oral)

2. Korean Physics Society Fall Meeting, “Pauli-limiting Effects in the Upper Critical Fields of a Clean LiFeAs Single Crystal” (Oral)

3. 11th Korea-Japan-Taiwan Symposium on Strongly Correlated Electron System: Also 8th Workshop for A3 Foresight Program, “Pauli limiting in the upper critical fields of a LiFeAs single crystal” (Poster)

 

2012

1. M2S2012, “Observation of anomalous magneto-resistance near the in-plane upper critical field in Sr(Fe,Ni)2As2 single crystals” (Poster)

2. RHMF2012, “High magnetic field properties of iron-based superconductors” (Oral)

 

2013

1. APS March Meeting in Baltimore, “Enhanced Upper Critical Fields in a New Quasi-one-dimensional Superconductor Nb2PdxSe5” (Oral)

 

Reference

Ph. D. Advisor: Professor Kee Hoon Kim, Department of Physics and Astronomy, Seoul National University, South Korea, khkim@phya.snu.ac.kr

Professor Greg Stewart, Department of Physics, University of Florida, USA,  stewart@phys.ufl.edu