The extrinsic origin of the magnetodielectric effect in the double perovskite La₂NiMnO₆

Abstract

A La(2)NiMnO(6) polycrystalline sample prepared by the sol-gel method showed monoclinic crystal structure with the P2(1)/n space group and a saturation magnetization of 4.63 μ(B)/f.u. at 5 K. Impedance spectroscopy results in the temperature range of 10 K < T < 300 K have revealed a distinct conduction process at grains and grain boundaries, where the grains followed the variable range hopping mechanism and the grain boundaries obeyed Arrhenius thermal activation. A negative magnetoresistance of 2.5% was observed at the paramagnetic to ferromagnetic transition, and this became temperature independent below the magnetic ordering. A marginal positive magnetodielectric (MD) effect that followed the dielectric relaxation was observed and its magnitude was found to decrease with increase of the frequency. A systematic study on the magnetic field induced dielectric properties, dc transport and dc bias effect on the dielectric permittivity has revealed the extrinsic origin of the MD effect in the bulk sample of La(2)NiMnO(6).

Functional properties of Sm2NiMnO6 multiferroic ceramics prepared by spark plasma sintering

“…Fig. 7 (b) presents the Arrhenius plot of the dc-conductivity of the Sm 2 NiMnO 6 ceramics, for which an activation energy of about ∼0.17eV was determined by linear regression analysis The activation energy for Sm 2 NiMnO 6 double perovskite ceramics is comparable with the activation energy of ∼0.14eV calculated from the dc-conductivity for Ho 2 NiTiO 6 perovskites reported by Mahato et al [30] or with the activation energies reported by Chandrasekhar et al [31] for La 2 NiMnO 6 double perovskites (values around M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 0.14eV and 0.119eV corresponding to the grain and grain boundary, respectively). Activation energies of about 0.17 eV were also reported for La 2 NiMnO 6 double perovskites [15].…”

Structural and transport properties of double perovskite Dy2NiMnO6

“…Multifunctional double perovskite oxides (DPOs) Ln 2 NiMnO 6 [Ln = lanthanides] have gained immense research interest in the recent years due to their rich physical properties which make them as the prospective materials for technological applications [1][2][3][4][5][6][7][8][9][10][11][12]. In this family La 2 NiMnO 6 having ferromagnetic order temperature of about 280 K is a rare example of a single material platform with multiple functions, in which the spins, electric charges, and dielectric properties can be tuned by magnetic and/or electric fields.…”

“…al [4]. These properties make this series of materials suitable for possible applications in spintronic devices, such as magnetic memories and magnetodielectric capacitors [2,6].…”

Passivation of the La2NiMnO6 double perovskite to hydroxylation by excess nickel, and the fate of the hydroxylated surface upon heating

“…Nickel precipitates, primarily as LaNiO 3 or La 2 NiO 4 , have been reported, but perhaps the most interesting is an amorphous form of La 2 O 3 , proposed as a sink for lanthanum to create vacancies in the perovskite but for which no direct information from X-ray diffraction (XRD) or other methods of analysis has yet been obtained. La 2 NiMnO 6 samples have been synthesized in single crystal [12], polycrystalline [4,13,14], nanoparticle [15,16] and thin film [4,[17][18][19][20] forms by a variety of methods. Despite their complicated and defect-prone nature, the composition and stability of the La 2 NiMnO 6 surface have received little attention.…”