Older News .. ;)

 
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Berufsinfotag am Gymnasium Julianeum in Helmstedt mit dem Vortrag: Physik - wiss. Grundlagen für die Welt von Morgen, 25.1.2017

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Junior Research Group Leader (TV-L 14) position is open (Ausschreibung, Announcement)

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Summertime means cryostat leak testing together with Arno Ellermann, head of the machinery shop, 1.8.2016

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Teilnahme am Impulsvortrag "Fair führen an der Universität", 14.12.2016 und dem Workshop "MitarbeiterInnengespräche in der Wissenschaft" beim Teach4TU, 29.6.2016

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Grundsteinlegung (und hier) von Lena, ein Zuhause für Nanomesstechnik, "Emergent Nanometrology", 18.4.2016

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Berufsinfotag am Gymnasium Julianeum in Helmstedt mit dem Vortrag: Physik - wiss. Grundlagen für die Welt von Morgen, 20.1.2016

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Misael Chavarria's farewell, Nov. 27, 2015

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with 4 presentations, coffee, cake, sweets, wine, and best wishes.

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Our visitor from Taipei (National University and Academica Sinica) explains us the properties of Weyl semimetals (from left to right: Liu Bio, Azat Sharafeev, Silvia Müllner, Raman Sankar, Robert Bohle, Peter Lemmens) 

We congratulate Silvia Müllner for her Bachelor presentation, 06.08.2015

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Two Lectures within IGSM: Scanning Probe Microscopies / Raman Scattering, 04.6.2015 / 16.7.2015

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Schnuppervorlesung: Energie und Ressourcen, HIT 2015, 29.5.2015

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8.-10.4.2015: Statusseminar der NANOMET, Haus Sonnenberg

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31.1.2015: Vortrag Physik am Samstag; Magnetismus ist mehr als Nord- und Südpol, TU Braunschweig, mit zahlreichen Experimenten von Th. Lampe email für pdf-Datei

 

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28.1.2015: Vortrag Physik, Grundlagen für die Welt von morgen, Berufsfindungstag, Julianeum, Helmstedt email für pdf-Datei

"Für diejenigen, die nach dem Abitur ein akademisches Studium anstreben, waren die Stände der Universitäten und Hochschulen von besonderem Informationswert. Ein Highlight war der Vortrag von Prof. Dr. Peter Lemmens, TU Braunschweig, der in seinem Vortrag „Physik, wissenschaftliche Grundlage für die Welt von morgen“ nicht nur über die zahlreichen Möglichkeiten für ein naturwissenschaftliches Studium dozierte, sondern auch verschiedene physikalische Phänomene erklärte und so auf ein naturwissenschaftliches Studium neugierig machte, ohne jedoch nicht auch auf den großen Mathematikanteil im Studium hinzuweisen." (Webseite des Julianeum)

 

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13.1.2015: New building and research center: Laboratory for Emergent Nanometrology

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10.07.2014: We congratulate Ms. Lakshmi Das for her DAAD-Fellowship to prepare parts of her Master Thesis in our group.

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1.6. und 30.6.2014: Evaluationen der VL Festkörperphysik und Nanotechnologie

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12.05.2014: NANOMET - We are a member of the newly founded RTG Graduate School of the DFG, Metrology of Complex Nanosystems, jointly with the PTB
 

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05.05.2014: We congratulate Kwang-Yong Choi for his AvH-Fellowship to be spend in our group on Correlation effects in Topological Insulators
 

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11.04.2014: The Lower Saxonian Graduation program, Interactions, Control and Quantum Dynamics starts
 

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08.04.2014: Laboratory for Emerging Nanometrology and Analytics starts
 

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18.01.2014: Infotag - Supraleitung, Elektronenpaare durch Dick und Dünn.

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17.1.2014: Jazz-Downtown at the Vielharmonie
 

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05.12.2013: Seminar at the Texas Center for Superconductivity TcSUH
 

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23.07.2013: Superconductivity and Iron, lecture at the ZFM-Hannover Summerschool  on Functional Solids, Goslar
 

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19.07.2013: Participation in "MOOC's at the TU Braunschweig"
 

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16.01.2013: Participation in the course "Lectures in a mobilizing way", Kompetenzzentrum Hochschuldidaktik Niedersachsen.
 

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16.04.2013: The nanoworld at your fingertips, with our new Plasma-enhanced Atomic Layer Deposition (ALD) we prepare novel metamaterials and devices. Project together with A. Waag and A. Bakin from IHT, TU-BS.

 

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26.1.2012: Physik - Schülerinformationstag und Exkursion mit dem Physik III Kurs ins Phaeno, 13.1.2012

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Wir danken Herr O. Stadel, Fa. Percotech und Fraunhofer IST, für den Demonstrator "Supraleitung in der Energietechnik", Photo: G. Dornig, EMG TU-BS.

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Congratulations to successful phd defences.
a) Dirk Wulferding, 05.07.2013,
b) Hongdan Yan, 7.8.2012 (Pict. by G. Dornig), c) Fatih Cetin, 18.10.2012 (Pict. by G. Dornig), d) Aidin Lak, 10.10.2013.

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Unnamed participants of the 27th Jazz and Rock Workshop in Salzgitter enjoy their music onstage (7.-10.6.2011).
 

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Recent results:

  There is a crossover from coherent to incoherent excitations in a Mott insulator with strong spin-orbit coupling. We demonstrate this effect as function of the excitation energy of the experiment. The modes of the J_eff=1/2 isospin states in Sr2IrO4 leads to characteristic resonances at the charge transfer energy, (Phys. Rev. B).

Editors Choice... Evidence for a Z2 quantum phase transition from a dimer to a resonating valence bond state driven by singlet fluctuations. The rich spectrum of singlet bound modes is attributed to a melting of a dimer crystal, see Phys. Rev. Lett. 110 (2013).

Surface engineering of various nanoparticles (NPs) is of growing interest and an important step to induce/control optical and/or catalytic activities. Here we report a top-down fabrication methodology to modify a model ferrofluid with parent NPs sizes ∼23 nm. The surface engineering involves “ligand exchange” and simultaneous “phase transfer”, and“core etching”, resulting in a reduction of particle diameter to ∼5 nm. We have used the functionalized NPs for the photodegradation of biomedically important jaundice marker bilirubin in aqueous solution. Overall, the results represent a promising route for the fabrication of NPs adaptable to diverse applications, see Journ. of Phys. Chem. C (2014).

Charge migration along DNA molecules is a key factor for DNA-based devices in optoelectronics and biotechnology. We have investigated the role of water molecules in DNA-based materials for the intactness of the DNA structure and their dynamic role in the charge-transfer (CT) dynamics. This study uses time resolved optical spectroscopy and is based on a collaboration between groups from Kolkata, Idia and the TU-Braunschweig, see Chemistry, An Asian Journal (2014).

Figure 5

In the giant Rashba system BiTeI as well as in topological insulator there exist an enhanced quasiparticle dynamics of quantum well states. This is due to a time dependent band beneding leading to a surface confined quantum well state. Topological insulators and Giant Rashba system share a very similar surface chemistry and strong spin orbit coupling of bulk and surface states. However, they have a different symmetry in the bulk. This leads to a different symmetry of electronic Raman scattering, see PRB.

A novel solid solution (Co1-xNix)3Sb4O6F6 with a pseudo kagome structure can be taylored with respect to its physical properties by changing its composition. This systems can be used to better understand the interplay of dimensionality, anisotroy and magnetism within one crystallographic structure. This is a collaboration between groups from Stockholm, Houston and Braunschweig, see Chem. of Mat., (2014).

The novel oxofluoride Cu7(TeO3)6F2 shows features of both zero and one dimensional magnetism. This is due to an interplay of composition that contains fluorine ions as well as the lone pair element Te with the electronic configuration of the Cu 3d orbitals. In contrast to many other compounds the fluorine terminates the magnetic exchange path. Te with its lone pair electrons opens up the structure like a scissor. The alternation of different Cu orbitals (see right figure) has a further important consequence for the exchange from one Cu2 sites (brown plaquette) to the other. As a result low energy fluctuations exist in a broad temperature range. This is a collaboration between groups from Stockholm, Houston and Braunschweig, see Inorganic Chemistry, (2014).
Dynamic lattice distortion and spin fluctuation cooperate in the spin liquid phase of a low-dimensional compound nitrosonium nitratocuprate. This system has been proposed to be a model compound for the resonanting valence bond ground state (RVB). Our data, however, point towards a structural instability at low temperatures that freezes out spin correlations by an excitation gap (Phys. Rev. B 85, (2012) and cond-mat).

The magnetoelectric compound Cu2OSeO3 shows a state with an inhomogenous spin polarization called SKYRMION phase. These objects are topologically protected and form a superstructure that can be investigated by small angle neutron scattering. The skyrmion phase in an insulator with coupled dielectric-spin degrees of freedom allows new applications in the field of spintronics (Phys. Rev. Lett).
Frustrated quantum spins realized by transition metal ions in solids form states of matter with novel properties. We show how a modification of the chemical composition in zinc paratacamite can be used to tailor its magnetic properties from a spin liquid to a spin glas (Phys. Rev. B and cond-mat).
Molecules that consist of three Cu ions and are arranged in a lattice (freestanding porous silicon) realize a novel hybrid material. It provides a promising scheme for implementing spin-based quantum gates. By measuring the spin relaxation times of samples with different symmetries and environments we give evidence that a spin chirality is the main decoherence source of spin triangle molecules (Phys. Rev. Lett.).
 
Topological insulators allow collision dominated scattering with spin-helical symmetry. This scattering is due to fluctuations from Dirac to bulk states of the compound despite topological protection. The scattering rate is determined from the position of a maximum in the RL scattering component as G=40cm-1 (Phys. Rev. B).
   

Magnetic molecules can be tuned by a confinement in the nanocage of a Protein, (Chem Phys Chem).

 

 


Webpages of Peter Lemmens

Diese Web-Seite stellt keine Meinungsäußerung der TU Braunschweig dar.

p.lemmens at tu-bs.de, letzte Änderung: 24.06.2015