Neutron and Mössbauer studies of FeCr2Se4

Fe Cr 2 Se 4 has been studied with x-ray and neutron diffraction techniques, superconducting quantum interference device magnetometer, and Mössbauer spectroscopy. The crystal structure of FeCr2Se4 at 295K is monoclinic (space group I2∕m), with the lattice parameters a=6.267Å, b=3.617Å, c=11.822Å, and β=90.69°, and its magnetic structure is found to be C-type ordering. The Mössbauer spectra were obtained at various temperatures ranging from 4.2to295K. Magnetic hyperfine and electric quadrupole interactions at 4.2K have been fitted, yielding the following results: Hhf=108.8kOe, θ=72°, φ=90°, η=0, ΔEQ=(1∕2)e2qQ[1+(1∕3)η2]1∕2=−1.65mm∕s, and R=−2.25. Our study strongly suggests that the quadrupole interaction of FeCr2Se4 is larger than the magnetic dipole interaction.