Chair News

© University of Augsburg

Dielectric ordering of water molecules arranged in a dipolar lattice

 

In a recently published paper in "Nature Communications", together with scientists from Moscow, Novosibirsk, Prague, and Stuttgart, we solve the long-standing question whether the dipolar water molecules can spontaneously order parallel, thus forming a ferroelectric state. Such an exotic state of water is thought to be of high relevance in various natural systems and also might enable future applications in biocompatible nanoelectronics. In a joint experimental effort, we could show that separate H2O molecules, enclosed within nanosized channels in a crystal of the beryl family, indeed can form such a state.

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Macroscopic manifestation of domain-wall magnetism and magnetoelectric effect in a Néel-type skyrmion host

 

Geometrical or dimensional constraints can promote the formation of new quantum phases which are absent in bulk systems. Such constraints can be imposed naturally via mesoscale domain patterns or topological defects on the atomic scale. By combination of detailed magnetoelectric and magnetic torque measurement and supported by neutron scattering and real space imaging experiments we found an additional magnetic state in Skyrmion host material GaV4Se8 which emerges at polar domain walls. A clear anomaly in the magneto-current indicates that the DW confined magnetic states also have strong contributions to the magnetoelectric response. We expect polar domain walls to commonly host such confined magnetic edge states and, thus, offer a fertile ground to explore novel forms of magnetism.

 

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Magnetoelectric spectroscopy of spin excitations in LiCoPO4

 

Magnetoelectric spectroscopy is a powerful tool to determine all off-diagonal elements of the magnetoelectric tensor in a contactless fashion. Our colleagues demonstrate the efficiency of this optical method by measuring the off-diagonal magnetoelectric response of LiCoPO4 in the GHz-THz regime. According to their finding, the magnetoelectric effect in this antiferromagnet is dominated by the symmetric (quadrupolar) part of the magnetoelectric tensor.

 

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Ferroelectricity in vectorchiral phases

 

Chirality, that is the handedness of objects is acknowledged for its great importance in many fields of biology and chemistry. However, chirality also plays a huge role in physical phenomena, e. g. symmetry aspects of frustrated magnets. In case of noncollinear magnetic ground states, spin-spirals may emerge. It is predicted for these states, that even above the magnetic ordering temperature, so-called vectorchiral phases emerge, which feature an ordered spin rotation (either of clockwise or anticlockwise fashion) between neighbouring spins, still there is no explicit relation concerning the angle spanned by neighbouring spins. By means of magnetic field dependent polarization measurements, we are the first to provide proof for the emergence of this phenomenon in LiCuVO4, a one dimensional quantum magnet with concurrent ferromagnetic and antiferromagnetic exchange interactions (marked as "VC" in the attached phase diagram). This proof relies on the fact that the vectorchiral state implies a finite ferroelectric polarization at temperatures above the ordering of the three dimensional spin-spirals.

 

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Optical pumping of magnetic skyrmions

GaV4S8 is a multiferroic semiconductor hosting magnetic cycloid (Cyc) and Néel-type skyrmion lattice (SkL) phases with a broad region of thermal and magnetic stability. Here, we use time-resolved magneto-optical Kerr spectroscopy to show the coherent generation of collective spin excitations in the Cyc and SkL phases. Our micromagnetic simulations reveal that these are driven by an optically induced modulation of uniaxial anisotropy. Our results shed light on spin dynamics in anisotropic materials hosting skyrmions and pave a new pathway for the optical manipulation of their magnetic order.

 

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Research Topics

Our group covers a broad field of investigations in condensed matter physics. We focus on new materials for future electronics, on unconventional ground states, superconductors, the dynamics of disordered matter and biological materials.

 

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© University of Augsburg
© University of Augsburg
© University of Augsburg

Experimental Methods

Aside of a large number of sample characterization methods, a strong point of our group is the combination of a variety of spectroscopic methods enabling deep insight into the microscopic properties of condensed matter. This not only includes dielectric, THz, and optical spectroscopy but also electron and nuclear magnetic resonance techniques.

 

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© University of Augsburg
© University of Augsburg
© University of Augsburg

National and International Collaborative Research Projects

Our group participates in several specially funded collaborative research projects:

© University of Augsburg

Sino-German Cooperation on Emergent Correlated Materials

The Sino-German Center for Research Promotion (SGC) is funding a cooperation project on electronically highly correlated materials, which is conducted by Zhejiang University (Hangzhou) and the University of Augsburg.

© University of Augsburg

Ressourcenstrategische Konzepte für zukunftsfähige Energiesysteme

The graduate school "Ressourcenstrategische Konzepte für zukunftsfähige Energiesysteme" provides funding for PhD students, who carry out research on essential topics regarding future energy and supply systems.

Contact

Secretariat
Experimental Physics V

General Contact Information:

Address (Secretary Office):
Anny Skroblies

(Room 308, 3rd floor)

Universitätsstrasse 1

D-86159 Augsburg

Germany


Telefon: +49 821 598 -3602

Fax: +49 821 598 -3649

E-Mail: anny.skroblies@physik.uni-augsburg.de


Mailing Address:

Experimentalphysik V

Institut für Physik

Universität Augsburg

Universitätsstrasse 2

D-86135 Augsburg

Germany


Delivery Address:

Experimentalphysik V

Institut für Physik

Universität Augsburg

Universitätsstrasse 1

D-86159 Augsburg

Germany


Map and Directions:

The Department of Experimental Physics V is located in the building S of the Institute of Physics at the University of Augsburg. The secretary's office is in room 308 on the 3rd floor.


How to reach us with public transportation:

From Munich Airport take the city train S8 or the Airport Bus to reach "München Hauptbahnhof". Then take the train to "Augsburg Hauptbahnhof".
From "Augsburg Hauptbahnhof" take the tram route 3 in the direction of "Haunstetten West". The tram stop "BBW/Institut für Physik" is located directly in front of the building.


How to reach us by car:

Leave the B17 at exit "Messe/Universität" and turn right into Universitätsstraße directly afterwards. After about 1 kilometer turn right into Hertha-Sponer-Weg between the buildings T and R.
Parking spaces are located along the buildings R and S as well as at the end of the street (P9).

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