Anomalous Fermi surface in FeSe seen by Shubnikov-de Haas oscillation   measurements
  We have observed Shubnikov-de Haas oscillations in FeSe. The Fermi surface deviates significantly from predictions of band-structure calculations and most likely consists of one electron and one hole thin cylinder. The carrier density is in the order of 0.01 carriers/ Fe, an order-of-magnitude smaller than predicted. Effective Fermi energies as small as 3.6 meV are estimated. These findings call for elaborate theoretical investigations incorporating both electronic correlations and orbital ordering. 
Taichi Terashima, Naoki Kikugawa, Andhika Kiswandhi, Eun-Sang Choi,   James S. Brooks, Shigeru Kasahara, Tatsuya Watashige, ...
cond-mat.supr-con cond-mat.str-el