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Felix Baumberger School of Physics and Astronomy, University of St. Andrews

Van Hove singularities and mass renormalization in the itinerant metamagnet Sr3Ru2O7


The layered perovskite Sr3Ru2O7 is a strongly enhanced paramagnet with a series of metamagnetic transitions in high field. Remarkably, these transitions enclose a putative electron nematic phase characterized by a reduced C2 symmetry of the in-plane resistivity in C4 symmetric RuO2 bilayers [1]. Several authors proposed that the existence of van Hove singularities in the density of states might drive this symmetry reduction by causing a Fermi surface instability or a particular orbital ordered state. I will present high-resolution ARPES experiments that unambiguously demonstrate the presence of singularities on the minute energy scale of metamagnetism – nearly three orders of magnitude below the non-interacting band width [2]. A strong and orbital dependent renormalization is instrumental in shifting the singularities towards the chemical potential. Our recent spectroscopic imaging STM results raise the prospect of following the evolution of the electronic structure with increasing field into the nematic state [3].

 

[1] R.A. Borzi et al. Science 315, 214 (2007)

[2] A. Tamai et al., Phys. Rev. Lett. 101, 026407 (2008)

[3] J.H. Lee, et al., Nat. Phys. 5, 800 (2009)

 

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