Quantum oscillation studies of the Fermi surface of iron-pnictide superconductors

Abstract

This paper reviews quantum oscillation studies of iron-pnictide superconductors and related materials. These measurements give unique information regarding the full three dimensional topology of the Fermi surfaces and the renormalisation of the quasi-particle masses. The review will cover measurements of the 122 arsenide end members, XFe_2As_2 (X = Ba, Sr, Ca) which have a spin density wave ground state, but will concentrate on the phosphide end members (LaFePO and XFe2P2) which have a paramagnetic ground state and a Fermi surface topology which is similar to the higher Tc superconducting iron-pnictides. All three of the 122 phosphides become superconducting when P is partially substituted by As, and for the BaFe2(As1-xPx)2 series de Haas-van Alphen oscillations are observable for 0:42 \leq x \leq 1 with Tc up to 25 K. The results show the changes in the Fermi surface topology and the increase in the mass renormalisation as the correlations which induce superconductivity develop.