Unusual Fermi surface reconstruction driven by moderate magnetic fields in Sr$_{4}$Ru$_{3}$O$_{10}$

Trilayered ruthenate Sr$_{4}$Ru$_{3}$O$_{10}$ exhibits puzzling magnetic properties. For field applied along the c-axis it exhibits typical itinerant ferromagnetic (FM) behavior, while moderate field (2-3T) applied within the \textit{ab}-plane can induce a metamagnetic (MM) transition [1]. Such coexistence of ferromagnetism and metamagnetism has been shown to be associated with a multiple band effect; FM bands derived from the $d_{xy}$ orbital coexists with MM bands from the $d_{xz,yz}$ orbitals [2,3]. In this talk, we report on Hall effect studies of this compound. Our results reveal that Fermi surface of Sr$_{4}$Ru$_{3}$O$_{10}$ changes dramatically through the MM transition. This Fermi surface change leads the Hall resistivity \textit{$\rho $}$_{xy}$ to strongly deviate from the scaling relation with magnetization, i.e. \textit{$\rho $}$_{xy}$ = $R_{0}H$ + 4$\pi R_{s}M$, which holds at fields well below and above the MM transition field. Such a significant change of the FS is unexpected for typical itinerant MM transitions.\\[4pt] [1] Cao \textit{et al}., Phys. Rev. B 68, 174409 (2003)\\[0pt] [2] J. Jo \textit{et al}., Phys. Rev. B 75, 094413 (2007)\\[0pt] [3] Fobes \textit{et al}., unpublished.