PREPRINTS

[22] Superfluid-like TO Responses in Rotating Solid Helium
      
J. Choi, T. Tsuiki, D. Takahashi, K. Kono, K. Shirahama, H. Choi and E. Kim 
     (in preparation)
 
[21] Scailing Analysis of Field-induced Superconductor-insulator Transition in
      Two-dimensional Tantalium Thin Films

      
S. Park and E. Kim, arxiv:1401.3947 (submitted)
  

PUBLISHED ARTICLES

[20] Simultaneous Investigation of Shear Modulus and Torsional Resonance of       Solid 4He
      
J. Shin, J. Choi, K. Shirahama and E. Kim
      Physical Review B 93, 214512 (2016)
   
[19] Evolution of Various Quantum Transport Properties in a Suspended
      Disordered Graphene Device by the High Bias Voltage Exposure

      
J. I. Lee, S. Jang, S. Cho and E. Kim
      Current Applied Physics 16, 731 (2016)
    
[18] Frequency-dependent Study of Solid He4 Contained in a Rigid Double-
      torus Torsional Oscillator

      
J. Choi, J. Shin and E. Kim
      Physical Review B 92, 144505 (2015)
   
[17] Modified Granato-Lucke Theory with Pinning Length Distribution
      in Solid 4He

      
E. S. H. Kang, H. Yoon, and E. Kim
      Journal of the Physical Society of Japan 84, 034602 (2015)
  
[16] Multi-barrier Field-emission Behavior in PBTTT Thin Films at Low
      Temperatures

      
E. S. H. Kang, and E. Kim
      Scientific Reports 5, 8396 (2015)
  
[15] Stress- and Temperature-dependent Hysteresis of the Shear
      Modulus of Solid 4He
     
 E. S. H. Kang, D. Y. Kim, H. C. Kim, and E. Kim
      
Physical Review B 87, 094512 (2013)
  
[14] Shear Resonance and Torsional Oscillator Measurements of Solid
      4He under DC Rotation

      
W. Choi, D. Takahashi, D. Y. Kim, H. Choi, K. Kono and E. Kim
      Physical Review B 86, 174505 (2012)
  
[13] Staircaselike Suppression of Supersolidity under Rotation
      
H. Choi, D. Takahashi, K. Kono and E. Kim
      Physical Review Letters 108, 105302 (2012)
  
[12] Effect of Non-isothermal Recrystallization on Microstrucutre and
      Transport in Poly(thieno-thiophene) Thin Films
     
 E. S. H. Kang, and E. Kim
      Organic Electronics 12, 1649-1656 (2011)
  
[11] Unaffected Nonclassical Response of Solid 4He under Elastic
      Modulus Variation

     
 D. Y. Kim, H. Choi, W. Choi, S. Kwon, E. Kim and H. C. Kim
      Physcal Review B 83, 052503 (2011)
  
[10] Evidence of Supersolidity in Rotating Solid Helium
      
H. Choi, D. Takahashi, K. Kono, and E. Kim
      Science 330, 1512-1515 (2010)
  
[9] Observation of Hidden Phases in Supersolid 4He
    
  H. Choi, S. Kwon, D. Y. Kim and E. Kim
      Nature Physics 6, 424-427 (2010)
  
[8] Amorphous Dithenylcyclopentadienone-carbazole Copolymers for       Organic Thin-film Transistor
      
E. S. H. Kang, J. D. Yuen, W. Walker, N. E. Coates, S. Cho, E. Kim and F. Wudl
      Journal of Materials Chemistry 20, 2759-2765 (2010)
  
[7] Non-classical Response from Quench-cooled Solid Helium Confined
      in a Porous Gold

      
D. Y. Kim, S. Kwon, H. Choi, H. C. Kim, and E. Kim
      New Journal of Physics 12, 033004 (2010)
  
[6] Absence of Slow Sound Modes in Supersolid 4He
      
S. Kwon, N. Mulders, and E. Kim
      Journal of Low Temperature Physics 158, 590-595 (2010)
  
[5] Effect of He3 Impurities on the Nonclassical Response to
     Oscillation of Solid He4

     
 E. Kim, J. S. Xia, J. T. West, X. Lin, A. C. Clarck, and M. H. W. Chan
      Physical Review Letters 100, 065301 (2008)
  
[4] Supersolid Helium at High Pressure
     
 E. Kim and M. H. W. Chan
      Physcal Review Letters
97, 115302 (2006)
  
[3] Observation of Non-classical Rotational Inertia in Solid 4He
      Confined in Porous Gold

    
  E. Kim and M. H. W. Chan
      Journal of Low Temperature Physics
138, 859-864 (2005)
  
[2] Observation of Superflow in Solid Helium
     
 E. Kim and M. H. W. Chan
      Science
305, 1941-1944 (2004)
  
[1] Probable Observation of a Supersolid Helium Phase
     
 E. Kim and M. H. W. Chan
      Nature
427, 225-227 (2004)

   

 
  Dr. Duk Young Kim (2010)
 

Non-classical Rotational Inertia and Shear Modulus of Solid Helium Download

   
  Dr. Wonsuk Choi (2013)
 

Non-classical Rotational Inertia and Acoustic Resonance Studies of Solid Helium under  Rotation Download

   
  Dr. Sun-Gyu Park (2014)
 

Quantum Phase Transition of 2D Tantalium Thin Film Tuned by B-field, Disorder, and Effect of DC Bias Download

   
  Dr. Evan S. Hyungoo Kang (2014)
 

Low-temperature Transport in Semiconducting Polymer Thin Films Download

   
  Dr. Jungil Lee (2016)
 

The Electronic Transport Properties of High-Bias-Voltage-Exposed Graphene Devices Download

   
  Dr. Jaeho Shin (2016)
 

Simultaneous Investigation of Shear Modulus and Torsional Resonance of Polycrystalline Solid Helium-4 Download

   
  Dr. Jaewon Choi (2016)
 

Search for Supersolid Helium by Using a Rigid Torsional Oscillator Download

   
 

   
 


 

SUPERSOLID AND SOLID HELIUM
Simultaneous Investigation of Shear Modulus and Torsional Resonance of Solid 4He
J. Shin, J. Choi, K. Shirahama and E. Kim
Physical Review B 93, 214512 (2016)

We investigate the origin of a resonant period drop of a torsional oscillator (TO) containing solid He4 by inspecting its relation to a change in elastic modulus. To understand this relationship directly, we measure both phenomena simultaneously using a TO with a pair of concentric piezoelectric transducers inserted in its annulus. We confirm experimentally that both anomalies are directly related. Although the temperature, He3 concentration, and frequency dependence are essentially the same, a marked discrepancy in the drive amplitude dependence is observed. We find that this discrepancy originates from the anisotropic response of polycrystalline solid He4 connected with low-angle grain boundaries by studying the shear modulus parallel to and perpendicular to the driving direction.

 

 

POLYMER PHYSICS
Multi-barrier Field-emission Behavior in PBTTT Thin Films at Low Temperatures
E. S. H. Kang and E. Kim
Scientific Reports 5, 8396 (2015)

We investigated the low-temperature transport mechanism for poly[2,5-bis(3-alkylthiophen 2-yl)thieno(3,2-b)thiophene] (PBTTT). The temperature-dependent transport behavior was studied by varying the drain–source electric field and gate bias. The results suggest that low-temperature charge transport is dominated by direct tunneling at low electric fields, while field emission is prevailing for high electric fields with high carrier densities. However, the obtained barrier heights are remarkably greater than expected in a conventional field emission. We propose a simplified model of field emission through quasi-one-dimensional path with multiple barriers which shows good agreement with the results more clearly. Field emission across the domain boundaries may assist in overcoming the transport barriers induced by the interchain disorder, which results in the weak temperature dependence of conductivities and nonlinear current–voltage relation at low temperatures.