Polaron Hopping Induced Giant Room‐Temperature Magnetodielectric Effect in Disordered Rutile NiNb₂O₆

Abstract

A majority of the existing magnetodielectric (MD) effects based on spin-lattice coupling or magnetic transitions are either too weak or far below room temperature, which challenges the potential applications of MD materials. Here, a giant room-temperature MD coefficient of −62% at 1 Tesla (T) in disordered rutile NiNb 2 O 6 (r-NiNb 2 O 6 ) ceramic in terms of the spin-dependent polaron hopping is demonstrated. The r-NiNb 2 O 6 exhibits a near-room-temperature dielectric relaxation, which is ascribed to the polaron-hopping-induced grain polarization. This dielectric relaxation process, strikingly, can be controlled by the external magnetic field (H = 1 T) at 220 K< T< 310 K, achieving a giant MD coefficient of −62% (at 10k Hz) at 298 K. Further systematic investigations on the magnetic, electrical, and magnetoelectric coupling properties attribute the MD effect in r-NiNb 2 O 6 to a pure response of the spin-dependent polaron hopping to applied magnetic field. This clearly reveals that the MD effect is subject to a competition among the polaron hopping activation, spin-lattice coupling, and spin thermal fluctuation.

Giant permittivity in (Nb0.5La0.5)xTi1‐xO2 ceramics prepared by slip casting in a strong magnetic field

“…20,49 The magnetic field may have oriented these defect clusters. In rutile NiNb 2 O 6 materials, the ion's spin alignment and the strength of the spin-lattice coupling are both influenced by the magnetic field that is being applied, 31 and modifying the dielectric response stands to reason. In (Nb 0.5 La 0.5 ) x Ti 1-x O 2 ceramics, the magnetic field may affect the defect clusters inside the ceramics, 30 thereby increasing R1 and R2's activation energy.…”

“…However, studies of improving giant permittivity performance via this method are rarely reported 30 . Due to the magnetic field having a regulatory effect on cluster defects 31 , magnetic slip casting is a promising approach to modify EPDD 30,32–35 …”

“…[27][28][29] However, studies of improving giant permittivity performance via this method are rarely reported. 30 Due to the magnetic field having a regulatory effect on cluster defects 31 , magnetic slip casting is a promising approach to modify EPDD. 30,[32][33][34][35] In this paper, a series of textured (Nb 0.5 La 0.5 ) x Ti 1-x O 2 (x is 0, 0.0025, 0.005, 0.01) samples were created by magnetic slip casting (12 T) and sintered in a nitrogen environment, explored how preparation conditions and doping amounts impacted the materials' microstructure, dielectric properties, and polarization mechanisms.…”

Dielectric phenomena of multiferroic oxides at acoustic- and radio-frequency

“…A view point should be set forth that the application objects of ECM do not only limit to the inhomogeneous systems. Moreover, ECM is also suitable to describe dipolar-type dielectric response in light of the equivalent circuit in the inset of figure 3 [144,147,230]. This equivalent circuit is the parallel of the capacitance C ∞ element and the series of the capacitance ∆C and a distributed CPE element, and the total admittance of this circuit can be obtained as:…”

“…The systematic analyses of the dielectric anomalies in broadband frequency range (from acoustic-to optical-frequency) are extremely significant and are able to provide one detailed and unique insight into abundant underlying fundamental physics. It involves phase transition , quantum paraelectric and quantum electric-dipole liquids [57][58][59][60][61][62][63][64][65][66], ferroic domain wall (DW) motion [67][68][69][70][71][72][73][74], short-range polar region, nano-microdomain and multiglass behaviors [29,, heterogeneous interface effects [51,, the origin of magnetoelectric and magnetodielectric (MD) phenomena [39-41, 48, 139, 140, 145-148], the motion of charged point defects and related defect complexes [115,143,, the transport mechanisms of localized charged carriers and polarons [24,138,144,147,164,169,, electronic phase separation [139,140], charge order-disorder [24,51,131,185], spin-lattice interaction [39,40,48], electron-phonon interaction [215], optical phonon soft modes [216], electronic critical points transitions [215,…”