Spin-lattice coupling and complex thermal expansion in Ca2FeAlO5.

High resolution x-ray diffraction, strain gauge and Raman spectroscopy measurements of Ca 2 FeAlO 5 as a function of temperature is reported, which provides the evidence of negative thermal expansion (NTE) and strong spin-lattice coupling in this compound. The unit cell showed a decrease in volume with increase in temperature with a distinct jump around 70 °C which corroborates with the magnetic ordering temperature and showed a contraction under magnetic field. The Raman spectra showed variation under magnetic field supporting spin-lattice coupling at room temperature. Most importantly, the NTE ( β ≅ − 6.41 × 10 −5 °C −1 ) is observed from room temperature up to ∼70 °C making it very attractive for applications. [ABSTRACT FROM AUTHOR]