### Session W13: Focus Session: Iron Pnictides and Other Novel Superconductors XIV: ARPES

11:15 AM–2:03 PM, Thursday, March 19, 2009
Room: 309

Chair: Norman Mannella, University of Tennessee, Knoxville

Abstract ID: BAPS.2009.MAR.W13.12

### Abstract: W13.00012 : Electronic properties of CaFe$_{2}$As$_{2}$

1:27 PM–1:39 PM

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#### Authors:

Chang Liu
(Ames Laboratory and Iowa State University)

Takeshi Kondo
(Ames Laboratory and Iowa State University)

Ari Palczewski
(Ames Laboratory and Iowa State University)

German Samolyuk
(Ames Laboratory and Iowa State University)

Yongbin Lee
(Ames Laboratory and Iowa State University)

Ni Ni
(Ames Laboratory and Iowa State University)

Sergey Bud'ko
(Ames Laboratory and Iowa State University)

Paul Canfield
(Ames Laboratory and Iowa State University)

CaFe$_{2}$As$_{2}$ is a parent compound of a new family of FeAs based high-$T_{c}$ superconductors. It undergoes a first-order structural transition from low-$T$ orthorhombic to high-$T$ tetragonal phase [Ni \textit{et al.}, Phys. Rev. B \textbf{78}, 014523]. Moderate pressure lowers the transition temperature, and turns on the superconductivity [Torikachvili \textit{et al.}, Phys. Rev. Lett. \textbf{101}, 057006]. Study on its electronic properties is of crucial importance for understanding the pairing mechanism of the FeAs based superconductors. Here we present angle-resolved photoemission spectroscopy (ARPES) results on both the orthorhombic and the tetragonal phase of CaFe$_{2}$As$_{2}$. In the orthorhombic phase, we find strong $k_{z}$ dispersion on the Fermi surfaces, showing a three dimensional electronic structure. We also find dramatic difference of the Fermi surface structure between the orthorhombic and the tetragonal phase.