Theory of magnetism in La${}_2$NiMnO${}_6$

Abstract

The magnetism of ordered and disordered La${}_2$NiMnO${}_6$ is explained using a model involving double exchange and superexchange. The concept of majority spin hybridization in the large coupling limit is used to explain the ferromagnetism of La${}_2$NiMnO${}_6$ as compared to the ferrimagnetism of Sr${}_2$FeMoO${}_6$. The ferromagnetic insulating ground state in the ordered phase is explained. The essential role played by the Ni-Mn superexchange between the Ni $e_g$ electron spins and the Mn $t_{2g}$ core electron spins in realizing this ground state, is outlined. In presence of antisite disorder, the model system is found to exhibit a tendency of becoming a spin-glass at low temperatures, while it continues to retain a ferromagnetic transition at higher temperatures, similar to recent experimental observations [D. Choudhury .et.al., Phys. Rev. Lett. 108, 127201 (2012)]. This reentrant spin-glass or reentrant ferromagnetic behaviour is explained in terms of the competition of the ferromagnetic double exchange between the Ni $e_g$ and the Mn $e_g$ electrons, and the ferromagnetic Ni-Mn superexchange, with the antiferromagnetic antisite Mn-Mn superexchange.

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References in corpus (4)

• Electronic Structure, Phonons and Dielectric Anomaly in Ferromagnetic Insulating Double Perovskite La2NiMnO6
• Phase transition in the three dimensional Heisenberg spin glass: Finite-size scaling analysis
• Theory of High T${}_c$ Ferrimagnetism in a Multi-orbital Mott Insulator
• Double perovskite heterostructures: Magnetism, Chern bands, and Chern insulators

Cited by in corpus (6)

• Colossal magnetoresistance in the insulating ferromagnetic double perovskites Tl${}_2$NiMnO${}_6$: A neutron diffraction study
• Mapping the magnetic state as a function of anti-site disorder in Sm${}_2$NiMnO${}_6$ double perovskite thin films
• Robust ferromagnetism in insulating La${}_2$NiMnO${}_6$ thin films
• Rare-earth tuned magnetism and magnetocaloric effects in double perovskites $R_2$NiMnO${}_6$
• Magnetic properties of disordered polycrystalline bulk Sm${}_2$NiMnO${}_6$ double perovskite
• Existence of inter coupled structural, electronic and magnetic states in Sm${}_2$NiMnO${}_6$ double perovskite