Three- to Two-Dimensional Transition of the Electronic Structure in CaFe2As2 - parent compound for an iron arsenic high temperature superconductor

TL;DR

This study uses ARPES to reveal a dimensional crossover in CaFe2As2's electronic structure during its structural and magnetic transition, highlighting the importance of low dimensionality in its superconducting properties.

Contribution

It demonstrates a 3D-2D electronic structure transition in CaFe2As2 associated with its phase transition, providing new insights into the role of dimensionality in pnictide superconductors.

Findings

Fermi surfaces are cylindrical and quasi-2D above Ts

Below Ts, Fermi surface around Gamma becomes 3D ellipsoid

Dimensionality change suggests low dimensionality influences superconductivity

Abstract

We use angle-resolved photoemission spectroscopy (ARPES) to study the electronic properties of CaFe2As2 - parent compound of a pnictide superconductor. We find that the structural and magnetic transition is accompanied by a three- to two-dimensional (3D-2D) crossover in the electronic structure. Above the transition temperature (Ts) Fermi surfaces around Gamma and X points are cylindrical and quasi-2D. Below Ts the former becomes a 3D ellipsoid, while the latter remains quasi-2D. This finding strongly suggests that low dimensionality plays an important role in understanding the superconducting mechanism in pnictides.