title: Three- to two-dimensional transition of the electronic structure in CaFe2As2: a parent compound for an iron arsenic high-temperature superconductor.
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 (T_{s}) Fermi surfaces around Gamma and X points are cylindrical and quasi 2D. Below T_{s}, the Gamma pocket forms a 3D ellipsoid, while the X pocket remains quasi 2D. This finding strongly suggests that low dimensionality plays an important role in understanding the superconducting mechanism in pnictides.
authors.affiliation: Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kondo
authors.forename: Ni
authors.initials: N
authors.lastname: Ni
authors.forename: A D
authors.initials: AD
authors.lastname: Palczewski
authors.forename: A
authors.initials: A
authors.lastname: Bostwick
authors.forename: G D
authors.initials: GD
authors.lastname: Samolyuk
authors.forename: R
authors.initials: R
authors.lastname: Khasanov
authors.forename: M
authors.initials: M
authors.lastname: Shi
authors.forename: E
authors.initials: E
authors.lastname: Rotenberg
authors.forename: S L
authors.initials: SL
authors.lastname: Bud'ko
authors.forename: P C
authors.initials: PC
authors.lastname: Canfield
authors.forename: A
authors.initials: A
authors.lastname: Kaminski