Anisotropic thermal expansion of AEFe2As2 (AE = Ba,Sr, Ca) single crystals |
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| Authors: | Sergey L Bud'ko Ni Ni Paul C Canfield |
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| Institution: | 1. Ames Laboratory US DOE and Department of Physics and Astronomy , Iowa State University , Ames, Iowa 50011, USA budko@ameslab.gov;3. Ames Laboratory US DOE and Department of Physics and Astronomy , Iowa State University , Ames, Iowa 50011, USA |
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| Abstract: | We report anisotropic thermal expansion of the parent, AEFe2As2 (AE = Ba, Sr, and Ca), compounds. Above the structural/antiferromagnetic phase transition anisotropy of the thermal expansion coefficients is observed, with the coefficient along the a-axis being significantly smaller than the coefficient for the c-axis. The high temperature (200 K ≤ T ≤ 300 K) coefficients themselves have similar values for the compounds studied. The sharp anomalies associated with the structural/antiferromagnetic phase transitions are clearly seen in the thermal expansion measurements. For all three pure compounds, the ‘average’ a-value increases and the c-lattice parameter decreases on warming through the transition, with the smallest change in the lattice parameters observed for SrFe2As2. The data are in general agreement with the literature data from X-ray and neutron diffraction experiments. |
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| Keywords: | iron-arsenides thermal expansion anisotropy structural phase transition |
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