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Publications

In-chain tunneling through charge-density-wave nanoconstrictions and break junctions

Cornell Affiliated Author(s)
Author
K. O'Neill
E. Slot
R.E. Thorne
H.S.J. Van Der Zant
Abstract

We have fabricated longitudinal nanoconstrictions in the charge-density wave conductor (CDW) NbSe3 using a focused ion beam and using a mechanically controlled break-junction technique. Conductance peaks are observed below the TP1=145K and TP2=59K CDW transitions, which correspond closely with previous values of the full CDW gaps 2Δ1 and 2Δ2 obtained from photoemission. These results can be explained by assuming CDW-CDW tunneling in the presence of an energy gap corrugation 2 comparable to Δ2, which eliminates expected peaks at ±|Δ1+Δ2|.

Journal
Physical Review Letters
Date Published
Group (Lab)
Robert Thorne Group

Visualizing dislocation nucleation by indenting colloidal crystals

Cornell Affiliated Author(s)
Author
P. Schall
Itai Cohen
D.A. Weitz
F. Spaepen
Abstract

The formation of dislocations is central to our understanding of yield, work hardening, fracture, and fatigue1 of crystalline materials. While dislocations have been studied extensively in conventional materials, recent results have shown that colloidal crystals offer a potential model system for visualizing their structure and dynamics directly in real space 2. Although thermal fluctuations are thought to play a critical role in the nucleation of these defects, it is difficult to observe them directly.

Journal
Nature
Date Published
Group (Lab)
Itai Cohen Group

Shear modulus and plasticity of a driven charge density wave

Cornell Affiliated Author(s)
Author
A.F. Isakovic
P.G. Evans
J. Kmetko
K. Cicak
Z. Cai
B. Lai
R.E. Thorne
Abstract

We have probed the effects of transverse variations in pinning strength on charge-density-wave (CDW) structure in NbSe3 by x-ray micro-beam diffraction. In ribbonlike crystals having a large longitudinal step in thickness, the CDW first depins on the thick side of the step, causing rotations of the CDW wave vector. By measuring these rotations as a function of position and electric field, the corresponding shear strains are determined, allowing the CDW's shear modulus to be estimated.

Journal
Physical Review Letters
Date Published
Group (Lab)
Robert Thorne Group

Fourier-transformed local density of states and tunneling into a d -wave superconductor with bosonic modes

Cornell Affiliated Author(s)
Author
J.-X. Zhu
A.V. Balatsky
T.P. Devereaux
Q. Si
J. Lee
K. McElroy
J.C. Davis
Abstract

We study the effects of the electronic coupling to bosonic modes on scanning tunneling microscopy (STM) into a d -wave superconductor. We propose to investigate these effects by means of a different technique: a Fourier transformed inelastic electron tunneling spectroscopy (FT-IETS). Specifically, in this technique, the Fourier spectrum of the energy derivative local density of states is addressed, which is proportional to the (d2 I d V2) (q,eV) characteristics measured in FT-IETS STM.

Journal
Physical Review B - Condensed Matter and Materials Physics
Date Published
Group (Lab)
J.C. Seamus Davis Group

Detection of forces and displacements along the axial direction in an optical trap

Cornell Affiliated Author(s)
Author
C. Deufel
M.D. Wang
Abstract

We present measurements of the forces on, and displacements of, an optically trapped bead along the propagation direction of the trapping laser beam (the axial direction). In a typical experimental configuration, the bead is trapped in an aqueous solution using an oil-immersion, high-numerical-aperture objective. This refractive index mismatch complicates axial calibrations due to both a shift of the trap center along the axial direction and spherical aberrations.

Journal
Biophysical Journal
Date Published
Research Area
Group (Lab)
Michelle Wang Group

Single electron tunneling in small molecules

Cornell Affiliated Author(s)
Author
M.R. Wegewijs
M.H. Hettler
C. Romeike
A. Thielmann
K. Nowack
J. König
Abstract

We discuss current- and noise-spectroscopy of small molecules weakly coupled to electrodes using master equations. The Coulomb interaction and size quantization effect on the molecule restrict the transport to the tunneling of single electrons. We consider situations where orbital-, spin- or vibrational excitations localized on the molecule play a role or even dominate the transport. For each case, we analyze mechanisms which lead to negative differential conductance (NDC) and even total suppression of the current.

Journal
Lecture Notes in Physics
Date Published
Group (Lab)
Katja Nowack Group

A history of the I-V characteristic of CDW conductors

Cornell Affiliated Author(s)
Author
R.E. Thorne
Abstract

The humble current-voltage (I-V) measurement has proven to be an extremely powerful probe of the physics of condensed matter systems from bulk semiconductors and superconductors to quantum dots and nanotubes. However, doing these deceptively simple measurements "right" so as to unambiguously extract particular bits of physics is hard. This is especially true of charge and spin density wave (CDW and SDW) conductors and related collective transport systems, in part because of the tremendous richness of their physics.

Conference Name
Conference
Date Published
Group (Lab)
Robert Thorne Group

Detection of high-affinity and sliding clamp modes for MSH2-MSH6 by single-molecule unzipping force analysis

Cornell Affiliated Author(s)
Author
J. Jiang
L. Bai
J.A. Surtees
Z. Gemici
M.D. Wang
E. Alani
Abstract

Mismatch repair (MMR) is initiated by MutS family proteins (MSH) that recognize DNA mismatches and recruit downstream repair factors. We used a single-molecule DNA-unzipping assay to probe interactions between S. cerevisiae MSH2-MSH6 and a variety of DNA mismatch substrates. This work revealed a high-specificity binding state of MSH proteins for mismatch DNA that was not observed in bulk assays and allowed us to measure the affinity of MSH2-MSH6 for mismatch DNA as well as its footprint on DNA surrounding the mismatch site.

Journal
Molecular Cell
Date Published
Research Area
Group (Lab)
Michelle Wang Group

Electrical transport through constrictions in the charge-density wave conductor NbSe 3

Cornell Affiliated Author(s)
Author
K. O'Neill
E. Slot
R. Thorne
H. Van Der Zant
Abstract

We have investigated the electrical transport properties of insulating and metallic constrictions of dimensions 10nm-10μm in the charge-density wave (CDW) conductor NbSe 3. The constrictions are made in a variety of ways: focused ion beam, reactive ion etching through a resist mask, and in a mechanically-controlled break junction configuration. We find that the behaviour of the junctions is independent of the fabrication method, and, depending on the size of the constriction, that the low-temperature behaviour of the constrictions is metallic or insulating.

Conference Name
Conference
Date Published
Group (Lab)
Robert Thorne Group

Enhancing drop stability in protein crystallization by chemical patterning

Cornell Affiliated Author(s)
Author
V. Berejnov
R.E. Thorne
Abstract

The motion of protein drops on crystallization media during routine handling is a major factor affecting the reproducibility of crystallization conditions. Drop stability can be enhanced by chemical patterning to more effectively pin the drop's contact line. As an example, a hydrophilic area is patterned on an initially flat hydrophobic glass slide. The drop remains confined to the hydrophilic area and the maximum drop size that remains stable when the slide is rotated to the vertical position increases.

Journal
Acta Crystallographica Section D: Biological Crystallography
Date Published
Research Area
Group (Lab)
Robert Thorne Group