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Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition

 

K. Glazyrin, L.V. Pourovskii, L. Dubrovinsky, O. Narygina, C. McCammon, B. Hewener, V. Schünemann, J. Wolny, K. Muffler, A. I. Chumakov, W. Crichton, M. Hanfland, V. Prakapenka, F. Tasnádi, M. Ekholm, M. Aichhorn, V. Vildosola, A. V. Ruban, M. I. Katsnelson, I. A. Abrikosov

Phys. Rev. Lett. 110 , 117206 (2013) 

 

Iron is the most abundant element on our planet. It is one of the most important technological materials and, at the same time, one of the most challenging elements for the modern theory. As a consequence, the study of iron and iron-based alloys has been a focus of experimental and computational research over the past decades. While the structural properties of iron and iron-nickel alloys at pressures below 100 GPa are well established, their electronic and magnetic properties are still debated. Our state-of–the-art ab initio calculations of the Fermi surface of Fe within the dynamical mean-field theory (DMFT) reveal a change of   its topology, the so-called   electronic topological transition (ETT) at pressures of about 30-40 GPa (see the figure). The ETT manifests itself through anomalous behavior of the Debye sound velocity, c/a lattice parameter ratio and Mössbauer center shift observed by our experimental colleagues. The ETT is absent in one-electron calculations (see the figure) and represents a clear evidence of the importance of correlation effects in Fe at high pressure.

The DMFT k-resolved spectral function (a and b), the corresponding one-electron band structures (c and d) and the DMFT Fermi surfaces (e and f) are shown for two volumes corresponding to low and high pressure. DMFT shows that ETT occurs around the L and G points.


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