Variable Temperature Scanning Tunneling Microscopy Study of a High Temperature Superconductor Bi2Sr2CaCu2O8+d
Vershinin, Michael
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/35235
Description
Title
Variable Temperature Scanning Tunneling Microscopy Study of a High Temperature Superconductor Bi2Sr2CaCu2O8+d
Author(s)
Vershinin, Michael
Issue Date
2004
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
temperature scanning
microscopy
superconductor
high temperature superconductor
scanning tunneling microscope
stm
spectroscopic
psuedogap energy
psuedogap phenomenology
spectroscopy
transfer line
dewar
UHV chamber
vibration isolation
scan head
topographic imaging
Bi2Sr2CaCu2O8+δ (BSCCO)
scattering interference models
Language
en
Abstract
We have used a custom-built scanning tunneling microscope (STM) to investigate
the electronic states of a slightly underdoped high-TC superconductor Bi2Sr2CaCu2O8+d as a function of temperature. We have demonstrated for the first time that atomicallyresolved
spectroscopic studies at elevated temperatures are possible. We have used this
new experimental capability to map out electronic states as a function of energy and
position at 40 K and 100 K. Atomically resolved spectroscopic mapping combined with
the analysis capabilities of Fourier-transform STM allow us to characterize electronic states both in real and reciprocal space. These techniques allow us to analyze our data in the context of many theoretical and experimental results and approaches. Our results confirm many aspects of prior observations at low temperatures. Specifically, our data at 40 K corroborates the identification and characterization of
impurity resonances at Zn and Ni sites, and the existence of dispersing modulations of
local electronic density of states below the superconducting gap energy. In this thesis, I
also present our observations and analysis of the few differences between our data at 40
K and preexisting low-temperature results.
The key results at 100 K are our observation of local electronic ordering below the pseudogap energy scale and our failure to observe any tell-tale signs of local
superconductivity at Ni impurity sites in the pseudogap regime of a high-TC superconductor. The observation of electronic ordering in the pseudogap regime is a novel and indeed a highly unexpected result. The existence of such a phenomenon is
likely to have substantial impact on our understanding of the pseudogap regime. Our
tunneling spectroscopy observations at the Ni sites reveal a clear difference between the electronic states above and below TC. This is a novel result in its own right. It
unambiguously shows that single electron spectroscopy can observe sharp differences
between the various cuprate phases. This observation makes STM a valuable tool and
holds the promise of using it to map out electronic states and phases across the entire phase diagram.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
