Magnetic susceptibilities, crystal field Stark energies, and hyperfine behavior of Sm3+ in hexagonal single crystals of Sm(CF3SO3)3⋅9H2O

Abstract

Single crystals of samarium trifluoromethanesulfonate (SmTFMS) were prepared from the slow evaporation of the aqueous solution of SmTFMS. The crystals are elongated along the symmetry axis c of the hexagonal crystal. At room temperature, the c axis of the crystal sets parallel with the applied magnetic field which indicates that the susceptibility parallel to the c axis (χ∥) is greater than the susceptibility perpendicular to the c axis (χ⊥). χ∥ and χ⊥ were measured from 300 down to 14 K. Magnetic anisotropy (Δχ=χ∥−χ⊥) obtained from the values of χ∥ and χ⊥ was also checked by direct measurements of Δχ and both these results agreed very well. A crossover between χ∥ and χ⊥ has been observed at ∼56 K i.e., below this temperature χ∥<χ⊥. A good theoretical simulation of the observed magnetic data of SmTFMS has been achieved using the one-electron crystal field (CF) theory. Ordering effects in the observed magnetic data were not noticed down to the lowest temperature (∼14 K) attained, indicating the interionic interaction to be of predominantly dipolar type. To substantiate the CF analysis, the Raman and Fourier transform infrared (FTIR) spectra of the single crystal of SmTFMS were recorded in the wave number ranges of 100–1800 and 400–7000 cm−1, respectively. The calculated values of the CF Stark energies of all the excited multiplets are in agreement with those extracted from the Raman and FTIR spectra. Thermal variation of the calculated electronic specific heat shows Schottky anomaly at ∼8 K. The temperature dependences of quadruple splitting and hyperfine heat capacity were also studied.