Magnetic and transport properties of the mixed 3d–5d–4f double perovskite Sm₂CoIrO₆

Abstract

Iridium-based double perovskites having mixed 3d-5d-4 f magnetic sub-lattices are expected to exhibit exotic magnetic phenomenon. In this paper, we report a study of structural, magnetic and transport properties of the mixed 3d-5d-4 f double perovskite Sm 2 CoIrO 6 (SMCO), which crystallizes in monoclinic structure with space group P2 1 /n and the crystal symmetry remains same throughout the measured temperature down to 15 K. High resolution synchrotron x-ray diffraction reveals an isostructural phase transition around 104 K. Magnetization measurements on polycrystalline samples indicate that SMCO orders ferrimagnetically at T FiM = 104 K; while, a second transition is observed below 10 K due to the rare-earth (Sm 3+ ) ordering. The ferrimagnetic transition is well-understood by Néel's two-sublattice model, which is primarily ascribed to antiferromagnetic coupling between Co 2+ and Ir 4+ sub-lattices. Electronic transport measurement shows the insulting behaviour of SMCO, which follows Mott variable-range hopping conduction mechanism. However, dielectric measurements as a function of temperature rules out the presence of magneto dielectric coupling in this compound.

A combined study on structural, magnetic and specific heat on double perovskite iridates Ln2CoIrO6 [Ln = Pr, Nd]

“…It is worthwhile to say that rare earth magnetic moment also affects the magnetic ground state. Ferrimagnetic (FiM) ground state along with low temperature rare earth ordering and a high value of dielectric permittivity at near room temperature is reported in Sm 2 CoIrO 6 , [16,17] where the A site cation (Sm 3+ ) is slightly magnetic(µ Sm 3+ = 0.85 µ B ). On the other hand, compounds with a highly magnetic A site cation such as DPs Tb 2 CoIrO 6 (µ Tb 3+ = 9.72 µ B and Ho 2 CoIrO 6 (µ Ho 3+ = 10.6 µ B ) exhibit a temperature-induced FiM-to-AFM magnetic phase transition and a field-induced spin-flop-like transition below AFM Néel temperature along with moderate magnetocaloric value [11].…”

Magnetic structure of the double perovskite La2NiIrO6 investigated using neutron diffraction

“…One such class of materials which sees a significant role of Ir in determining the magnetic and transport properties is formed by iridium-based double perovskites with the general formula A 2 BB O 6 with A = Ca, Ba, Sr, rare earth; B = magnetic 3d/4d ions and nonmagnetic ions, such as Zn, Mg, In; and B = Ir [17][18][19][20][21][22]. The ability of Ir to display different oxidation states, through doping and substitution at the A and B sites of the double-perovskite structure has resulted in a rich variety of properties [23].…”