올림픽 토토APCTP-POSTECH Distinguished Lecture[09.07.06]
관련링크
본문
"
“Carbon Nanotube Superconductivity: An Update”
ØSpeaker :Prof. Ping Sheng (HKUST, Clear Water Bay, Kowloon, Hong Kong)
ØPlace : #512, Hogil Kim Memorial Bldg., POSTECH
ØDate & Time : July 6 (Mon), 15:00 - 16:00
ØAbstract
Superconductivity in carbon nanotubes is a topic of intriguing interest.올림픽 토토While the small-diameter nanotubes
Are올림픽 토토predicted올림픽 토토to올림픽 토토have올림픽 토토enhanced올림픽 토토electron-phonon올림픽 토토coupling—a올림픽 토토key올림픽 토토element responsible올림픽 토토for올림픽 토토nanotube
superconductivitythe associated increase in fluctuation effects is unfavorable to the올림픽 토토manifestation올림픽 토토of올림픽 토토a
superconducting transition.올림픽 토토The possibility of a Peierls transition in thin nanotubes is a further올림픽 토토deterrent올림픽 토토to
superconductivity.올림픽 토토It올림픽 토토follows that the existence of coupling올림픽 토토between올림픽 토토the올림픽 토토nanotubes올림픽 토토is올림픽 토토important올림픽 토토to올림픽 토토the
realization of its superconducting behavior, since the transverse coherence can suppress올림픽 토토fluctuations올림픽 토토and
lower the Peierls transition temperature, thereby making the올림픽 토토appearance올림픽 토토of올림픽 토토a올림픽 토토superconducting올림픽 토토transition
possible.올림픽 토토 Owing to올림픽 토토its올림픽 토토ordered올림픽 토토and올림픽 토토closely-spaced올림픽 토토pore올림픽 토토structure (with올림픽 토토a올림픽 토토13.6올림픽 토토Å올림픽 토토center-to-center
separation between the 0.7 nm diameter pores), the AFI zeolite (composition: Al12P12O48) with embedded
4-Å carbon nanotubes constitutes an ideal material올림픽 토토for올림픽 토토the올림픽 토토observation올림픽 토토of올림픽 토토nanotube올림픽 토토superconductivity.
In this talk올림픽 토토I올림픽 토토will올림픽 토토describe올림픽 토토the올림픽 토토eight-year effort올림픽 토토that올림픽 토토resulted올림픽 토토in올림픽 토토the올림픽 토토two올림픽 토토new올림픽 토토developments올림픽 토토in올림픽 토토2007
(on improved sample fabrication) and올림픽 토토2008 (on making electrical contacts),올림픽 토토leading올림픽 토토to올림픽 토토reasonably올림픽 토토easy
observation of nanotube올림픽 토토superconductivity with high reliability올림픽 토토and올림픽 토토repeatability.올림픽 토토I n particular,올림픽 토토we올림픽 토토have
measured the specific heat signal for the superconducting transition as well as the resistive superconducting
transition.올림픽 토토The coupled carbon nanotube arrays can yield both nearly 1D superconducting behavior as well
as the Josephson array behavior, with their attendant magnetic characteristics.올림픽 토토The overall physical picture
that emerges is that of a coupled Josephson array consisting of aligned nanotubes crossing over from올림픽 토토an
individually fluctuating 1D system to a coherent 3D superconductor, mediated by a Kosterlitz-Thouless (KT)
transition which establishes quasi long range order in the lateral plane perpendicular to the올림픽 토토c-axis올림픽 토토of올림픽 토토the
nanotubes.올림픽 토토The attainment of global coherence is seen at 5K and below, accompanied by the appearance
of a well-defined supercurrent gap at 2K.올림픽 토토While the existence of the superconducting transition in nanotube
arrays is now beyond reasonable doubt, there are still many aspects올림픽 토토of올림픽 토토the올림픽 토토data올림픽 토토which올림픽 토토have올림픽 토토yet올림픽 토토to올림픽 토토be
theoretically understood.올림픽 토토I will present some important lessons learned from the eight-year effort and what
they tell us about the mesoscopic electronic states in most carbon nanotubes.올림픽 토토In particular, these lessons
may shed light on why nanotube superconductivity was not observed and/or confirmed earlier.
Contact Person : Prof. Wokyung Sung(054-279-2061, wsung@postech.ac.kr)"
“Carbon Nanotube Superconductivity: An Update”
ØSpeaker :Prof. Ping Sheng (HKUST, Clear Water Bay, Kowloon, Hong Kong)
ØPlace : #512, Hogil Kim Memorial Bldg., POSTECH
ØDate & Time : July 6 (Mon), 15:00 - 16:00
ØAbstract
Superconductivity in carbon nanotubes is a topic of intriguing interest.올림픽 토토While the small-diameter nanotubes
Are올림픽 토토predicted올림픽 토토to올림픽 토토have올림픽 토토enhanced올림픽 토토electron-phonon올림픽 토토coupling—a올림픽 토토key올림픽 토토element responsible올림픽 토토for올림픽 토토nanotube
superconductivitythe associated increase in fluctuation effects is unfavorable to the올림픽 토토manifestation올림픽 토토of올림픽 토토a
superconducting transition.올림픽 토토The possibility of a Peierls transition in thin nanotubes is a further올림픽 토토deterrent올림픽 토토to
superconductivity.올림픽 토토It올림픽 토토follows that the existence of coupling올림픽 토토between올림픽 토토the올림픽 토토nanotubes올림픽 토토is올림픽 토토important올림픽 토토to올림픽 토토the
realization of its superconducting behavior, since the transverse coherence can suppress올림픽 토토fluctuations올림픽 토토and
lower the Peierls transition temperature, thereby making the올림픽 토토appearance올림픽 토토of올림픽 토토a올림픽 토토superconducting올림픽 토토transition
possible.올림픽 토토 Owing to올림픽 토토its올림픽 토토ordered올림픽 토토and올림픽 토토closely-spaced올림픽 토토pore올림픽 토토structure (with올림픽 토토a올림픽 토토13.6올림픽 토토Å올림픽 토토center-to-center
separation between the 0.7 nm diameter pores), the AFI zeolite (composition: Al12P12O48) with embedded
4-Å carbon nanotubes constitutes an ideal material올림픽 토토for올림픽 토토the올림픽 토토observation올림픽 토토of올림픽 토토nanotube올림픽 토토superconductivity.
In this talk올림픽 토토I올림픽 토토will올림픽 토토describe올림픽 토토the올림픽 토토eight-year effort올림픽 토토that올림픽 토토resulted올림픽 토토in올림픽 토토the올림픽 토토two올림픽 토토new올림픽 토토developments올림픽 토토in올림픽 토토2007
(on improved sample fabrication) and올림픽 토토2008 (on making electrical contacts),올림픽 토토leading올림픽 토토to올림픽 토토reasonably올림픽 토토easy
observation of nanotube올림픽 토토superconductivity with high reliability올림픽 토토and올림픽 토토repeatability.올림픽 토토I n particular,올림픽 토토we올림픽 토토have
measured the specific heat signal for the superconducting transition as well as the resistive superconducting
transition.올림픽 토토The coupled carbon nanotube arrays can yield both nearly 1D superconducting behavior as well
as the Josephson array behavior, with their attendant magnetic characteristics.올림픽 토토The overall physical picture
that emerges is that of a coupled Josephson array consisting of aligned nanotubes crossing over from올림픽 토토an
individually fluctuating 1D system to a coherent 3D superconductor, mediated by a Kosterlitz-Thouless (KT)
transition which establishes quasi long range order in the lateral plane perpendicular to the올림픽 토토c-axis올림픽 토토of올림픽 토토the
nanotubes.올림픽 토토The attainment of global coherence is seen at 5K and below, accompanied by the appearance
of a well-defined supercurrent gap at 2K.올림픽 토토While the existence of the superconducting transition in nanotube
arrays is now beyond reasonable doubt, there are still many aspects올림픽 토토of올림픽 토토the올림픽 토토data올림픽 토토which올림픽 토토have올림픽 토토yet올림픽 토토to올림픽 토토be
theoretically understood.올림픽 토토I will present some important lessons learned from the eight-year effort and what
they tell us about the mesoscopic electronic states in most carbon nanotubes.올림픽 토토In particular, these lessons
may shed light on why nanotube superconductivity was not observed and/or confirmed earlier.
Contact Person : Prof. Wokyung Sung(054-279-2061, wsung@postech.ac.kr)"
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