Research Highlights

POSTECH Alumni at SLAC National Accelerator Laboratory Discover a New High-Temperature Superconductor

2015-11-26 403
 Dr. Jun-Sik Lee

Superconductivity, loss of electric resistance below critical temperature, is one of the most interesting and challenging topics in modern condensed matter physics. Superconductivity can be applied to electric power transfer without energy loss, and generating high magnetic field for MRI and magnetic levitation. Although it has been almost 30 years after the discovery of the high-temperature superconductivity (HTSC) in copper oxide compounds, their complex and puzzling properties are yet fully solved.
 
A team led by Dr. Jun-Sik Lee at SLAC National Accelerator Laboratory in the United States, who is a POSTECH alumnus (2006) of the Department of Physics, recently discovered a veiled three-dimensional charge density wave (CDW) in a high-temperature superconductor, yttrium barium copper oxide (YBCO), using x-ray free electron laser (FEL) and pulsed high magnetic field. This result was published in the journal Science, November 2015.
 
Currently, the CDW, which is a periodic modulation of electronic charge in high temperature superconducting cuprates, is considered as a universal feature and one of key clues for solving the mystery of HTSC. Many of studies on the CDW in superconductors have been done, implying that CDW is a two-dimensional feature. Dr. Lee said, “This result is kind of a breakthrough, and therefore, this discovery provides a new insight of the HTSC to this research community”. Also, quite naturally, this finding motivates completely new theoretical approaches. This result was realized by innovating experimental approaches – combination of the two pulses between the brightest x-ray pulse at Linac Coherent Light Source (LCLS)/ SLAC, as like a new 4th generation x-ray source at Pohang Accelerator Laboratory (PAL), and the high power pulsed magnet.
 
“This approach bridges the gap between previous experiments, low magnetic field x-ray scattering and high magnetic field nuclear magnetic resonance, and finally provides a clearer picture of charge density wave in the high-temperature superconductor,” said Dr. Hoyoung Jang at SSRL/SLAC, the lead author of this paper, who is also a POSTECH alumnus (2011) of the Department of Physics.