News from the Physics of Correlated Department

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Inauguration of the new MPI-NSRRC beamline in Taiwan

May 10, 2019
The newly constructed MPI-NSRRC TPS 45A beamline has been inaugurated on 7-May-2019 in the presence of the German Ambassador in Taiwan and the Deputy Minister of the Taiwan Ministry of Science and Technology. [more]
Teaser 1553767965

New method for imaging electronic orbitals in solids

March 26, 2019
A collaboration of the Max-Planck Institute for Chemical Physics of Solids, the University of Heidelberg, and the University of Cologne has developed a new method for imaging electronic orbitals in solids at the German Electron Synchrotron DESY in Hamburg.  [more]
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Revealing the topological nature of the surface states in SmB6

November 09, 2018
The topological nature of the surface states in SmB6 is exposed by means of scanning tunneling spectroscopy on samples with magnetic substituents or by using magnetic tunneling tips. These local measurements are complemented by global transport measurements on identical samples. [more]
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A universal strategy to design superior water splitting electrocatalysts with in situ fast surface reconstruction

October 05, 2018
A universal strategy based on electrochemically induced fast reconstruction of amorphous nanofilm precursors is proposed for exploring ultrahigh mass activity and extremely stable bifunctional water splitting catalysts. The facile reconstruction strategy is promising for the development of novel efficient catalysts for other advanced energy conversion and storage devices. [more]
Teaser 1534757847

From single-ion Kondo effect to Kondo lattice formation

August 20, 2018
Scanning tunneling spectroscopy data on the archetypical heavy fermion metal YbRh2Si2 establish a hierarchy of energy scales, with the dominance of the lattice Kondo effect requiring temperatures well (about an order of magnitude) below the single-ion Kondo temperature of about 25 K. Only if the lattice Kondo correlations are sufficiently established, quantum critical fluctuations can evolve. [more]
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Visualizing polaron formation in EuB6

June 26, 2018
A combination of scanning tunneling microscopy and locally resolved magnetic stray field measurements unambiguously revealed the polaron formation in the ferromagnetic semimetal EuB6. These polarons are at the heart of the colossal magnetoresistive effects near the ferromagnetic transition in this material. [more]
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c-axis dimer and its electronic breakup: The insulator-to-metal transition in Ti2O3

April 05, 2018
New X-ray spectra of the electronic structure of the transition metal oxide Ti2O3 reveal unprecedented electronic molecular detail about the transition from insulator to metal as temperature increases. [more]
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Ground state wave function of the strongly correlated topological insulator SmB6

January 08, 2018
SmB6 is under focus because it may be the first topological insulator that is also strongly correlated. It is intermediate valent and a gap opens only at low temperatures due to an intricate interplay between correlation effects and hybridization, yet the surface is always conducting. The topological properties of the surface are determined by the bulk so that it is surprising that the bulk crystal-field ground state of Sm3+ was unknown until now despite many attempts by e.g. neutron scattering. Recently, scientists from the Max-Planck Institute for Chemical Physics of Solids and the University of Cologne clarified this issue by applying a new technique, namely core-level non-resonant inelastic x-ray scattering, see Sundermann et al., Phys. Rev. Letter 120, 016402 (2018). The finding that the ground state is the Γ8 quartet and not the Γ7 doublet, contradicts all existing band structure calculations and illustrates in a sobering manner the difficulties in making reliable predictions for the properties of correlated systems. [more]
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LaNiO3: a highly metallic strongly correlated oxide with antiferromagnetic correlations

January 08, 2018
The rare earth nickelates RNiO3 with the high Ni3+ oxidation state have continued to attract enormous interest due to the famous metal-insulator transition and unusual charge and spin-order phenomena together with the prediction for multi-ferroicity and even superconductivity in thin film hetero-structures. One of the long standing puzzles is why LaNiO3 seems to be the only RNiO3 that stays metallic and paramagnetic down to lowest temperatures. Recently, the team around Alexander Komarek was able to grow centimeter-sized and impurity-free single crystals of LaNiO3 and then to unveil its true electrical and magnetic properties. The result is that the phase diagram of the RNiO3 system has to be redrawn and that theoretical concepts have to be reconsidered about how to explain the properties and the electronic structure of these high oxidation state materials. [more]
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New features in multipolar heavy-fermion materials

November 10, 2017
The simple cubic structure of CeB6 does not change while intricate multipolar phenomena are developed upon a non-magnetic La substitution. However, phase diagrams of Ce1-xLaxB6 have been elusive for the last decades. Recently, detailed phase transitions in Ce1-xLaxB6 have been revealed by scientists of MPI-CPfS, TU-Dresden, and I. M. Frantsevich Institute. In addition, a simple feature which is likely to be observed in a multipolar heavy-fermion system has been found.  [more]
Teaser 1508741912

Dr. Steffen Wirth zum Fellow der American Physical Society (APS) gewählt

October 20, 2017
Steffen Wirth erhält die Fellowship für „seine grundlegenden Beiträge zu unserem Verständnis von stark korrelierten Elektronensystemen, insbesondere bei reduzierten Längenskalen, einschließlich des Kondo-Effekts und magnetischer Wechselwirkungen", wie es in der Ernennungsurkunde heißt.  [more]
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Announcement of the Max Planck Center with POSTECH and NSRRC/NTCU/NTHU

January 16, 2017
Press Conference at the Ministry of Science and Technology of Taiwan 4 January 2017 in Taipeh [more]
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Press Release: Fe3O4 thin films: controlling and manipulating an elusive quantum material

December 12, 2016
Fe3O4 (magnetite) is one of the most elusive quantum materials as well as one of the most studied transition metal oxide for thin film applications. Yet, despite the tremendous amount of work devoted to preparing magnetite thin films, the enigmatic Verwey transition is in thin films extremely broad and occurs at substantially lower temperatures than that in bulk crystals. Recently, scientists at MPI CPfS have succeeded in growing magnetite thin films which not only have the Verwey transition as sharp as in the bulk, but also show transition temperatures that are substantially higher than the bulk. [more]
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Press Release: When being superficial becomes a virtue

December 12, 2016
SmB6 is predicted to be a candidate material for a topological Kondo insulator. By utilizing scanning tunneling spectroscopy (STS) down to 0.35 K with energy resolution of ~0.5 meV, we determined the electronic fine structure on large, non-reconstructed surfaces. Impurity, magnetic-field and temperature dependent STS spectra revealed bulk and/or surface contributions to the electronic states, and unveiled a new energy scale of >7 K related to a suppressed Kondo effect at the surface of SmB6. [more]
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Press Release: Hidden order and 5f electron density

November 23, 2016
URu2Si2 undergoes a mysterious ordering transition at 17 K which challenges theoretical and experimental physicists since more than thirty years. By now is generally understood that the distribution of the uranium electron density plays a key role, however, measuring these has so far not been possible. Recently, scientists from MPI-CPfS, University of Cologne and Van-der-Waals-Zeeman Institute in Amsterdam were able to measure these charge distributions by means of inelastic x-ray scattering.  [more]
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