Samarium Magnetism Studied on SmPd$_{2}$Al$_{3}$ Single Crystal J. Posp´ıˇ sil, 1,$_{∗}$ M. Kratochv´ılov´ a, 1 J. Prokleˇ ska, 1 M. Diviˇ s, 1 and V. Sechovsk´ y 1 $^{1}$Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 121 16 Prague 2, The Czech Republic (Dated: December 4, 2013) In this paper, specific features of Sm magnetism in an intermetallic compound have been studied. For this purpose, a high quality single crystal of SmPd$_{2}$Al$_{3}$ was grown and subjected to detailed measurements of specific heat, magnetization, AC susceptibility and electrical resistivity with re- spect to temperature and a magnetic field applied along the principal crystallographic directions. SmPd$_{2}$Al$_{3}$ magnetism was found to be strongly anisotropic with the easy-magnetization direction along the c -axis where the main magnetic features are concentrated. The a -axis response remains weak, paramagnetic-like, even in the magnetically ordered state. Ferromagnetism with T C = 12.4 K has been indicated by all the measured physical properties. At lower temperatures, three succes- sive order-order phase transitions have been observed on the temperature dependence of the specific heat as three anomalies: at 3.4, 3.9, 4.4 K, respectively. The low temperature magnetization data can be understood within a scenario that considers the antiferromagnetic ground state as being gradually destroyed through a series of four metamagnetic transitions at 0.03, 0.35, 0.5 and 0.75 T, as detected in the 1.8-K magnetization data. The temperature dependence of the paramagnetic susceptibility below 200 K can be in the first approximation interpreted in terms of a Curie-Weiss law modified by temperature independent van Vleck contribution due to the low-lying first excited multiplet J = 7/2 being populated. At higher temperatures, involvement of the second excited multiplet J = 9/2 should also be considered. The experimental data are discussed together with the results of electronic-structure and crystal-field calculations from first principles, which were performed as an important part of the study for comprehension and explanation of the observed behavior of the SmPd$_{2}$Al$_{3}$ compound. PACS numbers: 75.30.-m; 75.40.Cx; 1 arXiv:1001.4409v1 [cond-mat.str-el] 25 Jan 2010 Abstract