@article{BistiRogalevKarolaketal.2017,
  author    = {Bisti, F. and Rogalev, V. A. and Karolak, M. and Paul, S. and Gupta, A. and Schmitt, T. and G{\"u}ntherodt, G. and Eyert, V. and Sangiovanni, G. and Profeta, G. and Strocov, V. N.},
  title     = {Weakly-correlated nature of ferromagnetism in nonsymmorphic CrO\(_2\) revealed by bulk-sensitive soft-X-ray ARPES},
  series = {Physical Review X},
  volume    = {7},
  journal   = {Physical Review X},
  number    = {4},
  doi       = {10.1103/PhysRevX.7.041067},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172251},
  year      = {2017},
  abstract  = {Chromium dioxide CrO\(_2\) belongs to a class of materials called ferromagnetic half-metals, whose peculiar aspect is that they act as a metal in one spin orientation and as a semiconductor or insulator in the opposite one. Despite numerous experimental and theoretical studies motivated by technologically important applications of this material in spintronics, its fundamental properties such as momentumresolved electron dispersions and the Fermi surface have so far remained experimentally inaccessible because of metastability of its surface, which instantly reduces to amorphous Cr\(_2\)O\(_3\). In this work, we demonstrate that direct access to the native electronic structure of CrO\(_2\) can be achieved with soft-x-ray angle-resolved photoemission spectroscopy whose large probing depth penetrates through the Cr\(_2\)O\(_3\) layer. For the first time, the electronic dispersions and Fermi surface of CrO\(_2\) are measured, which are fundamental prerequisites to solve the long debate on the nature of electronic correlations in this material. Since density functional theory augmented by a relatively weak local Coulomb repulsion gives an exhaustive description of our spectroscopic data, we rule out strong-coupling theories of CrO\(_2\). Crucial for the correct interpretation of our experimental data in terms of the valence-band dispersions is the understanding of a nontrivial spectral response of CrO\(_2\) caused by interference effects in the photoemission process originating from the nonsymmorphic space group of the rutile crystal structure of CrO\(_2\).},
  language  = {en}
}
@article{HausoelKarolakŞaşιoğluetal.2017,
  author    = {Hausoel, A. and Karolak, M. and Şa{\c{s}}ιoğlu, E. and Lichtenstein, A. and Held, K. and Katanin, A. and Toschi, A. and Sangiovanni, G.},
  title     = {Local magnetic moments in iron and nickel at ambient and Earth's core conditions},
  series = {Nature Communications},
  volume    = {8},
  journal   = {Nature Communications},
  number    = {16062},
  doi       = {10.1038/ncomms16062},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170681},
  year      = {2017},
  abstract  = {Some Bravais lattices have a particular geometry that can slow down the motion of Bloch electrons by pre-localization due to the band-structure properties. Another known source of electronic localization in solids is the Coulomb repulsion in partially filled d or f orbitals, which leads to the formation of local magnetic moments. The combination of these two effects is usually considered of little relevance to strongly correlated materials. Here we show that it represents, instead, the underlying physical mechanism in two of the most important ferromagnets: nickel and iron. In nickel, the van Hove singularity has an unexpected impact on the magnetism. As a result, the electron-electron scattering rate is linear in temperature, in violation of the conventional Landau theory of metals. This is true even at Earth's core pressures, at which iron is instead a good Fermi liquid. The importance of nickel in models of geomagnetism may have therefore to be reconsidered.},
  language  = {en}
}