@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} } @article{HsuKuegelKemmeretal.2016, author = {Hsu, Pin-Jui and K{\"u}gel, Jens and Kemmer, Jeannette and Toldin, Francesco Parisen and Mauerer, Tobias and Vogt, Matthias and Assaad, Fakher and Bode, Matthias}, title = {Coexistence of charge and ferromagnetic order in fcc Fe}, series = {Nature Communications}, volume = {7}, journal = {Nature Communications}, doi = {10.1038/ncomms10949}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173969}, year = {2016}, abstract = {Phase coexistence phenomena have been intensively studied in strongly correlated materials where several ordered states simultaneously occur or compete. Material properties critically depend on external parameters and boundary conditions, where tiny changes result in qualitatively different ground states. However, up to date, phase coexistence phenomena have exclusively been reported for complex compounds composed of multiple elements. Here we show that charge- and magnetically ordered states coexist in double-layer Fe/Rh(001). Scanning tunnelling microscopy and spectroscopy measurements reveal periodic charge-order stripes below a temperature of 130 K. Close to liquid helium temperature, they are superimposed by ferromagnetic domains as observed by spin-polarized scanning tunnelling microscopy. Temperature-dependent measurements reveal a pronounced cross-talk between charge and spin order at the ferromagnetic ordering temperature about 70 K, which is successfully modelled within an effective Ginzburg-Landau ansatz including sixth-order terms. Our results show that subtle balance between structural modifications can lead to competing ordering phenomena.}, language = {en} }