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Publications highlights

Multiband charge density wave exposed in a transition metal dichalcogenide

Nature Communications 12, 6037 (2021)

In the presence of multiple bands, well-known electronic instabilities may acquire new complexity. While multiband superconductivity is the subject of extensive studies, the possibility of multiband charge...

Wang-MacDonald d-wave vortex cores observed in heavily overdoped Bi2Sr2CaCu2O8+δ

Phys. Rev. X 11, 031040 (2021)

The electronic structure of the vortex cores in copper oxide high temperature superconductors (HTS) is a long-standing puzzle. Using scanning tunneling spectroscopy at an unprecedented low magnetic field for...

Insight into the Charge Density Wave Gap from Contrast Inversion in Topographic STM Images

Phys. Rev. Lett. 125, 267603 (2020)

We present a first detailed study of the charge density wave (CDW) contrast inversion in scanning tunneling microscopy (STM) images. Combining high resolution STM imaging at different tunneling biases and...

Holographic imaging of the complex charge density wave order parameter

Phys. Rev. Research 1, 033114 (2019)

Combining real space and reciprocal space analysis of scanning tunneling microscopy images of transition metal dichalcogenides, we obtain real space maps of the amplitude, phase and periodicity of the complex ...

Energy-dependent spatial texturing of charge order in 1T-CuxTiSe2

Phys. Rev. B 99, 155133 (2019)

Scanning tunneling microscopy unveils an unusual energy dependent CDW pattern in Cu intercalated TiSe2. It is a direct manifestation of a large doping dependent CDW gap opening below the Fermi level.

Observation of Caroli–de Gennes–Matricon Vortex States in YBa2Cu3O7-δ

Phys. Rev. Lett. 119, 237001 (2017)

Detailed scanning tunneling microsccopy and spectroscopy and original model calculations reveal the long sought after electronic signature of the vortex cores in a high temperature copper oxyde d-wave...

Dimensional crossover of the charge density wave transition in thin exfoliated VSe2

2D Materials 4, 041005 (2017)

Scanning tunneling microscopy of in-situ exfoliated VSe2 reveals a non monotonic thickness dependence of the charge density wave (CDW) order parameter and phase transition temperature. Both parameters are...

Subatomic electronic feature from dynamic motion of Si dimer defects in Bi nanolines on Si(001)

Phys. Rev. B 96, 075304

Reduced dimensions can give rise to surprising effects. While a long exposure time photograph of a macroscopic moving object appears blurred, scanning tunneling microscopy images of flipping Si dimer defects...

Stripe and Short Range Order in the Charge Density Wave of 1T-CuxTiSe2

Phys. Rev. Lett. 118, 017002

Combining scanning tunneling microscopy (STM) and density functional theory, we unambiguously identify Cu intercalated on the octahedral site in the van der Waals gap of 1T-CuxTiSe2. STM imaging shows that at ...

Revisiting the vortex-core tunnelling spectroscopy in YBa2Cu3O7−δ

Nat. Commun. 7, 11139 (2016)

Scanning tunnelling spectroscopy on very homogeneous Y123 at 0.4K lift the veil on the vortex core spectroscopy. We find that the subgap features which have been challenging theoretical modelling for over...

Structure of Self-Assembled Mn Atom Chains on Si(001)

Phys. Rev. Lett. 115, 256104

Combining scanning tunneling microscopy, atomic force microscopy, and density functional theory we find that a simple necklacelike chain of single Mn atoms reproduces all the prominent features of Mn atom...

Scanning tunneling microscopy of the charge density wave in 1T−TiSe2 in the presence of single atom defects

Phys. Rev. B 92, 081101(R)

The charge density wave (CDW) in 1T-TiSe2 is imaged by scanning tunneling microscopy in the presence of single atom defects. The detailed identification of the defects by means of density functional theory...

Doping Nature of Native Defects in 1T−TiSe2

Phys. Rev. Lett. 112, 197001 (2014)

The structural and doping nature of native atomic defects in TiSe2 are identified and characterized using scanning tunneling microscopy or spectroscopy and ab initio calculations. The dominant single atom...

Half-filled orbital and unconventional geometry of a common dopant in Si(001)

Phys. Rev. B 88, 035440 (2013)

In this study, we find that isolated heavy dopants behave entirely different at the surface compared to the bulk and to lighter dopants. The common light impurity P replaces individual Si atoms and maintains...

Scalable Patterning of One-Dimensional Dangling Bond Rows on Hydrogenated Si(001)

ACS Nano 2013, 7, 5, 4422–442

Hydrogen dangling bonds are highly reactive and their selective exposure on hydrogenated Si(001) using scanning probes is developing as a powerful lithography to pattern molecules and atoms. We have found...

Piezoresistance in Silicon at Uniaxial Compressive Stresses up to 3 GPa

Phys. Rev. Lett. 108, 256801 (2012)

Measuring the piezoresistance in p-type silicon up to 3GPa, we found it to decrease with compressive stress beyond the predicted saturation. This result has potential implications for the Si technology...

Charge density waves in the graphene sheets of the superconductor CaC6

Nature Communications. 2011, vol. 2, 558

One dimensional charge density wave discovered by scanning tunneling microscopy in CaC6, a superconducting graphite intercalate compound.

Endotaxial Si nanolines in Si(001):H

Phys. Rev. B 84, 035328 (2011)

A one dimensional electronic state has been uncovered along the core of a self assembled endotaxial Si nanoline at the Si(001):H surface, with a range of promising properties to explore 1D physics.

Imaging oxygen defects and their motion at a manganite surface

Nature Communications. 2011, vol. 2, 212

The oxygen migration scenario for electroresistive switching in manganites gets new support. Mobile oxygen adatoms and defects have been observed by scanning tunneling microscopy with atomic resolution at the ...

Giant Piezoresistance Effects in Silicon Nanowires and Microwires

Phys. Rev. Lett. 105, 226802 (2010)

Migrating surface charges can simulate the giant piezoresistance observed in silicon nano- and micro-structures. See also comments in APS Physics Synopsis, Nature Materials Research Highlight and Physics...

Hands-on inspiration for science

Nature Materials 8, 245–247 (2009)

The PhysiScope draws the attention of Nature Materials.

Giant Room-Temperature Piezoresistance in a Metal-Silicon Hybrid Structure

Phys. Rev. Lett. 100, 145501 (2008)

Giant piezoresistance observed in a metal silicon hybrid structure. Article was featured in AIP Physics News Update.