Crystal and Magnetic Structures of La₂CoPtO₆ Double Perovskite

Abstract

We investigated the crystal structure and magnetic structure in cobaltite-platinate double perovskite of La 2 CoPtO 6 , employing various techniques of X-ray diffraction, neutron diffraction, and the extended X-ray absorption fine structure analysis. It is shown that the crystal symmetry is maintained as P 2 1 / n in the temperature range of <500 °C, whereas the lattice constants and the Co–Co distances undergo a continuous structural evolution toward the high-symmetry phases with increasing temperature. The Co–O bonds were overall longer and had a larger degree of structural and thermal disorders than the Pt–O bonds. As for the magnetism, an antiferromagnetic order is stabilized in the Co 2+ sublattice at temperatures below 28 K. It is demonstrated that owing to the substantial distortions (quantified by a distortion parameter Σ > 0.03 Å) of the Co–Co networks, the system is not subject to spin frustration effect. Details in the magnetic structure are determined; at 12 K, the Co magnetic moment was (0.8, 0, 2.7) Bohr magneton, the magnetic propagation vector was (−0.5, 0, 0.5), and the magnetic symmetry was preferably Γ 1 (A g ).

Insulator-to-metal transition, magnetic anisotropy, and improved TC in a ferrimagnetic La2CoIrO6: strain influence

“…= formula unit) less than that of the FM, AFM-I, and AFM-II, respectively, which is in good agreement with the experimental observations. 31,33,43,44 Therefore, only FiM order is taken into account for the electronic structure investigation, which exhibits a semiconducting nature with a very small E g of 0.35 eV as shown in the total density of states (TDOS) displayed in Fig. 2(a).…”

“…For example, a very high T C of 635 K 7 /725 K 9 is observed in the Sr 2 CrReO 6 /Sr 2 CrOsO 6 motif. Similarly, the La 2 CoPtO 6 system maintained a monoclinic phase up to a very high T C of ∼773 K. 27 Above room temperature (350 K), ferrimagnetic (FiM) behavior is dominant in Ca 2 FeOsO 6 DPO, which is owing to a strong antiferromagnetic (AFM) coupling between Fe and Os ions. 28 Due to strong SOC effects, the Ca 2 TMOsO 6 (TM = Co and Ni) structures exhibit a Mott-insulating state.…”

“…24 In this regard, La 2 CoIrO 6 material also shows interesting phenomena because of the numerous Co spin (valence) states and it has an insulating FiM ground state which is associated with a strong AFM interaction between Co 2+ and Ir 4+ ions. [31][32][33][34] Besides, it is also proposed that the Co 2+ 3d t 5 2g orbitals not only hybridize with the more than halfoccupied Ir 4+ 5d t 5 2g orbitals but also couple with the fully unoccupied e 0 g states of Ir and result in a paramagnetic state of La 2 CoIrO 6 .…”

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

“…In case of La 2 CoIrO 6 , which crystallizes in a monoclinic crystal structure with space group P2 1 /n, the interaction between Ir 4+ and Co 2+ is AFM and is an insulating system exhibiting magnetodielectric effect at low temperature as predicted by Song et al [8]. Consideration of two AFM sublattices were suggested from the neutron diffraction results of Lee et al [9] as well as from the studies of x-ray magnetic circular dichroism, Raman, and muon spin rotation and relaxation performed by Bufaiçal et al [10]. In addition, the above mentioned compound shows the formation of reentrant spin glass while Eu 2 CoIrO 6 shows Van Vleck paramagnetism, where Eu 3+ is a non-magnetic cation (4f 6 , S = 3, L = 3, J = 0, µ Eu 3+ = 0 µ B ) [11].…”

Interplay of valence states and magnetic interactions in the perovskite system LaNi1Rh O3

“…In terms of electronic properties, no detailed studies are performed on La2NiPtO6. However, La2CoPtO6 is reported to be antiferromagnetic below 28 K [134].…”