DFT & Electron Holography

Just accepted in Physical Review Letters!

Quantitative agreement between electron-optical phase images of WSe2 and simulations based on electrostatic potentials that include bonding effects

S. Borghardt, F. Winkler, Z. Zanolli, M. J. Verstraete, J. Barthel, A. H. Tavabi, R. E. Dunin-Borkowski, and B. Kardynal

The quantitative analysis of electron-optical phase images recorded using off-axis electron holography often relies on the use of computer simulations of electron propagation through a sample. However, simulations that make use of the independent atom approximation are known to overestimate experimental phase shifts by approximately 10%, as they neglect bonding effects. Here, we compare experimental and simulated phase images for few-layer WSe2. We show that a combination of pseudopotentials and all-electron density functional theory calculations can be used to obtain accurate mean electron phases, as well as improved atomic-resolution spatial distribution of the electron phase. The comparison demonstrates a perfect contrast match between experimental and simulated atomic-resolution phase images for a sample of precisely known thickness. The low computational cost of this approach makes it suitable for the analysis of large electronic systems, including defects, substitutional atoms and material interfaces.

More details soon! Stay tuned!

2017_01_18_prl_sven_just_accepted_title

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Metal-Insulator in semiconductor surfaces

Just published! Quasi-One-Dimensional Metal-Insulator Transitions in Compound Semiconductor Surfaces.

Existing examples of Peierls-type 1D systems on surfaces involve depositing metallic overlayers on semiconducting substrates, in particular, at step edges. Here we propose a new class of Peierls system on the (10-10) surface of metal-anion wurtzite semiconductors. When the anions are bonded to hydrogen or lithium atoms, we obtain rows of threefold coordinated metal atoms that act as one-atom-wide metallic structures. First-principles calculations show that the surface is metallic, and below a certain critical temperature the surface will condense to a semiconducting state. The idea of surface scaffolding is introduced in which the rows are constrained to move along simple up-down and/or sideways displacements, mirroring the paradigm envisioned in Peierls’s description. We predict that this type of insulating state should be visible in the partially hydrogenated (10-10) surface of many wurtzite compounds.

2016_prl_zhao

Ball-and-stick model of a GaN surface with H or Li atoms. Our test cases for metal-insulator phase transition. [Zhao et al Phys. Rev. Lett. 117, 116101]

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Spintronics by Design

My work “Graphene-multiferroic interfaces for spintronics applications” has just been published on Scientific Reports. First principles calculations tell us the best way to combine the properties of two class of materials – graphene and multiferroics – in a new hybrid structure that takes the best of both worlds: high carrier velocity from graphene & magnetism form the BaMnO3 substrate.

gBMO_spin_up-down

Spin density (ρ↑ – ρ↓) induced in the graphene lattice by the BaMnO3 substrate [Z. Zanolli Sci. Rep. 6:31346, DOI: 10.1038/srep31346 ]

Posted in graphene, magnetism, multiferroics, nanoscience, publication, Scientific Reports, spintronics, Zeila | Tagged , , , , , | Leave a comment

May 31st: deadline for the 21st ETSF workshop

Dear Theoretical Spectroscopy Scientist,

the deadline to submit an abstract to the 21ETSF workshop is approaching fast!

We need *you* to make it a successful meeting.  But – most important –
you need this workshop to

– showcase your best work not only to the ETSF community but also to
renowned experts in the field
– kickstart new collaborations with experimentalists
– get to know the MAX IV synchrotron
– sit at the same table with industry leaders
– discuss work opportunities in the industry
– live networking
– experience an amazing social program
– get your next job or project partner

Don’t wait the for the deadline! Submit your contribution now!

Registration & Info:  https://workshop.etsf.eu/
Date: 19 – 23 September, 2016
Place: Lund, Sweden
Deadline: the day before yesterday!

Looking forward to meet all of you in Lund!
The Organizing Committee
Ferdi, Claudio, Martin, Zeila, Nicole, Gabriele, and Michiel

Chirurgia

Lunds Kirurgisk Klinik (1867). Photo: Z. Zanolli

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Harry Kroto

A simple thought for Harry Kroto, 1996 Nobel Prize in Chemistry with Curl and Smalley for the discovery of C60 – fullerene. Graphics is my own.

HarryKroto

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21st ETSF Workshop on Electronic Excitations: Dynamics and spectroscopy of correlated systems

Download here the poster announcement (A3 format) of the 21st ETSF Workshop on Electronic Excitations! The workshop, which focuses on the Dynamics and Spectroscopy of Correlated Systems, will be held in Lund, 19-23 September 2016.

ETSF21-lund2016.png

Registration is open at https://workshop.etsf.eu/.

Important dates:
May 31, 2016: abstract submission deadline (oral)
July 15, 2016: end of early bird fee
August 16, 2016: room reservation deadline

Confirmed Invited Speakers:
Igor A. Abrikosov (Linköping University, Linköping, Sweden)
Silke Biermann (Ecole Politechnique, Universite Paris-Saclay, Palaiseau, France)
Anders Blom (QuantumWise, Sweden)
Pascale Deen (European Spallation Source, Lund, Sweden and University of Copenhagen, Copenhagen, Denmark)
Anna Delin (KTH Royal Institute of Technology, Stockholm, Sweden)
Hubert Ebert (Ludwig-Maximilian Universität, München, Germany)
Mechthild Enderle (Institut Laue-Langevin, Grenoble, France)
Gerrit van der Laan (Diamond Light Source, UK)
Dook van Mechelen (ABB Corporate Research, Switzerland)
Anders Mikkelsen (Lund University, Lund, Sweden)
Silvia Picozzi (Consiglio Nazionale delle Ricerche (CNR-SPIN), Chieti, Italy)
Gianluca Stefanucci (University of Tor Vergata, Rome, Italy)
Liu Hao Tjeng (Max Planck Institute for Chemical Physics of Solids, Dresden, Germany)

The Organizing Committee
Ferdi Aryasetiawan (University of Lund)
Claudio Verdozzi (University of Lund)
Martin Stankovski (University of Lund)
Zeila Zanolli (RWTH Aachen)
Nicole Helbig (Forschungszentrum Jülich)
Gabriele D’Avino (Mons University)
Michiel van Setten (Universite Catholique de Louvain)

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21st ETSF Workshop: Registration Open!

Registration is open for the 21st edition of the ETSF Workshop!
The workshop will be held at Lund University, on September 19 – 23, 2016.
This year topic is “Dynamics and spectroscopy of correlated systems”.

Please see below a list of important dates and invited speakers.
More details and registration information can be found at
https://workshop.etsf.eu/

Important dates:
May 31, 2016:    abstract submission deadline (oral contribution)
June 20, 2016:   communication of acceptance
July 15, 2016:     end of early bird fee
August 1, 2016:  poster contribution deadline
August 16, 2016: room reservation deadline
September 19 – 23, 2016:  Workshop!

Invited Speakers:
Hubert Ebert  (Ludwig-Maximilian Universität, München, Germany)
Silvia Picozzi  (Universita’ degli Studi di L’Aquila, L’Aquila, Italy)
Anna Delin   (KTH Royal Institute of Technology, Stockholm, Sweden)
Igor A. Abrikosov (Linköping University, Linköping, Sweden)
Silke Biermann   (Ecole Politechnique, Universite Paris-Saclay,
Palaiseau, France)
Gerrit van der Laan (Diamond Light Source, UK)
Gianluca Stefanucci (University of Tor Vergata, Rome, Italy)
Yoshinori Tokura*  (University of Tokyo, Tokyo, Japan)
Liu Hao Tjeng (Max Planck Institute for Chemical Physics of Solids,
Dresden, Germany)
Anders Mikkelsen (Lund University, Lund, Sweden)
Mechthild Enderle (Institut Laue-Langevin, Grenoble, France)
Pascale Deen (European Spallation Source, Lund, Sweden and University
of Copenhagen, Copenhagen, Denmark)

*(to be confirmed)

Looking forward to meet you in Lund!

The Organizing Committee:
Ferdi Aryasetiawan, University of Lund
Claudio Verdozzi, University of Lund
Martin Stankovski, University of Lund
Zeila Zanolli, University of Liege
Nicole Helbig Forschungszentrum Jülich
Gabriele D’Avino, Mons University
Michiel van Setten, Universite Catholique de Louvain

eden_av_m9b1880

Eden, the 21st ETSF workshop location

Posted in ab initio, ETSF, magnetism, multiferroics, quantum transport, spectroscopy, Zeila | Tagged , , , , , , , , , | Leave a comment