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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.

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Single crystals of thulium trifluoromethanesulfonate (TmTFMS) were grown and the principal magnetic susceptibility χ⊥ and magnetic anisotropy Δχ(=χ∥−χ⊥) were measured in the temperature range of 300–13.5K and 300–80K, respectively. Though the value of χ⊥ is found to rapidly increase with the decrease in temperature, the value of χ∥ slowly increases with the lowering of temperature down to ∼110K, below which it slowly decreases. The hexagonal crystal structure of TmTFMS is similar to that of the isostructural series of hydrated rare earth ethylsulfates and the non-Kramers Tm3+ ion occupies a site of C3h symmetry. Our observed magnetic data were analyzed using crystal field (CF) analyses where the Hamiltonian includes the atomic free ion and (CF) (one-electron) interaction terms. The computed and measured paramagnetic susceptibilities of TmTFMS agree well in the temperature range of our study. Smooth variation of χ⊥ down to 13.5K does not indicate any structural phase transition or symmetry breaking, at least down to 13.5K. The computed nuclear quadruple splitting and electronic heat capacities give some interesting results. In order to substantiate the theoretical calculation, the Raman spectra of the compound were recorded in the wavenumber range of 10–1800cm−1. It has been found that the theoretical values of the CF Stark energies in the ground multiplet are in good agreement with the Raman data.

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