Investigating the magnetic and magnetocaloric behaviors of LiSm(PO3)4

We report a detailed study on the magnetic behaviors and magnetocaloric (MC) effect of a single crystal of lithium samarium tetraphosphate, LiSm(PO3)(4). The analyses of temperature-dependent magnetization data have revealed magnetic ordering established with decreasing temperature below T-p, where T-p is the minimum of a dM/dT vs. T curve and varies as a linear function of the applied field H. The Curie temperature has been extrapolated from T-p(H) data, as H -> 0, to be about 0.51 K. The establishment of magnetic-ordering causes a substantial change in the heat capacity C-p. Above T-p, the crystal exhibits paramagnetic behavior. Using the Curie-Weiss (CW) law and Arrott plots, we have found the crystal to have a CW temperature theta(CW) approximate to -36 K, and short-range magnetic order associated with a coexistence of antiferromagnetic and ferromagnetic interactions ascribed to the couplings of magnetic dipoles and octupoles at the Gamma(7) and Gamma(8) states. An assessment of the MC effect has shown increases in value of the absolute magnetic-entropy change (|Delta S-m|) and adiabatic-temperature change (Delta T-ad) when lowering the temperature to 2 K, and increasing the magnetic-field H magnitude. Around 2 K, the maximum value of |Delta S-m| is about 3.6 J kg(-1) K-1 for the field H = 50 kOe, and Delta T-ad is about 5.8 K for H = 20 kOe, with the relative cooling power (RCP) of similar to 82.5 J kg(-1). In spite of a low MC effect in comparison to Li(Gd,Tb,Ho)(PO3)(4), the absence of magnetic hysteresis reflects that LiSm(PO3)(4) is also a candidate for low-temperature MC applications below 25 K.

Automated summary

We conducted a detailed study on the magnetic behaviors and magnetothermal effects of a single crystal of lithium samarium tetraphosphate, LiSm(PO3)(4). The temperature-dependent magnetization data analysis revealed the establishment of magnetic ordering below T-p, where T-p is the minimum of the dM/dT vs. T curve and varies linearly with the applied field H. The crystal exhibits paramagnetic behavior above T-p, and a coexistence of antiferromagnetic and ferromagnetic interactions is observed due to the couplings of magnetic dipoles and octupoles at the Gamma(7) and Gamma(8) states. Evaluation of the magnetocaloric effect showed an increase in the value of the absolute magnetic-entropy change and adiabatic-temperature change at lower temperatures and higher magnetic field magnitudes.