Short-range antiferromagnetic interaction and spin-phonon coupling in La2CoMnO6 double perovskite

arXiv:1802.07326v3Weak antiferromagnetic (AFM) interaction in the ferromagnetic (FM) partially ordered La2CoMnO6 (LCMO) was detected by Raman spectroscopy by monitoring spin-phonon coupling. Because of the sensibility to probe short-range disorder and lattice modifications, the Raman spectroscopy showed to be an useful tool to indicate less remarkable magnetic transitions in LCMO compound. Apart from the expected spin-phonon coupling due to the long-range FM superexchange (Tc ∼230 K), phonons parameters pointed out an additional spin-phonon coupling related to the short-range AFM interaction at Tc ∼135 K, which was not detected from the magnetic bulk response. These results reinforce the Raman spectroscopy as a powerful technique to detect antisite disorder into A2B′B’’O6 magnetic double perovskites, whose magnetic properties are driven by superexchange interactions.The authors thank the Brazilian agencies, Conselho Nacional de Desenvolvimento Científico e Tecnológico- CNPq, Brazil (UNIVERSAL 431943/2016-8, PQ - 305806/2020-3), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES, Brazil, Fundação de Amparo à Pesquisa do Estado de Minas Gerais - FAPEMIG, Brazil, Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico - FUNCAP, Brazil, and Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão - FAPEMA, Brazil (UNIVERSAL-01290/2016; INFRA-02050/21; BPD-05073/21) for co-funding this work.Peer reviewe

Room-temperature vibrational properties of the BiMn2O5 mullite

Raman and infrared spectroscopic measurements were performed and combined with lattice dynamics simulations in order to describe the room temperature vibrational properties of the BiMn2O5 mullite ceramic. A total of 13 Raman active modes and 19 infrared active modes were observed. The lattice dynamics simulation was used to assign the observed bands and to discuss the phonon behavior of this compound. The obtained dielectric constant and unloaded quality factor parameters for BMO ceramic obtained from the infrared data suggest the applicability of the BiMn2O5 as a possible candidate to microwave applications