Multiferroicity in a spin-chain compound, Tb2BaCoO5, with exceptionally large magnetodielectric coupling in polycrystalline form

Abstract

We report the results of detailed investigations of magnetization, heat-capacity, dielectric, pyrocurrent, and magneto(di)electric measurements on Tb2BaCoO5, belonging to a hither-to-unexplored spin-chain cobaltate family, R2BaCoO5 (R= Rare-earths). The magnetic measurements reveal that this compound exhibits an antiferromagnetic transition at (TN=) 18.8 K and there is a spin reorientation beyond 40 kOe below TN. Dielectric and pyrocurrent data measured as a function of temperature and magnetic-field establish that this compound is a 'type-II' multiferroic material. The most fascinating finding which we would like to emphasize is that the observed value of magneto-dielectric effect beyond the metamagnetic transition field is the largest (close to 55%, below 10 K, for H= ~100 kOe) ever reported for polycrystals of a compound in bulk form, thereby offering a hope to find a single-phase polycrystalline compound at room temperature to enable ease of applications.

High-temperature ferroelectric order and magnetoelectric coupling driven by the magnetic field cooling effect in R2BaCuO5(R=Er,Dy,Sm)<

“…Recently, the spin-chain compounds R 2 BaNiO 5 [26][27][28][29][30][31] and R 2 BaCoO 5 [32] attract special attention in multiferroics, proposing different origins behind the occurrence of ferroelectric order. In this study, we also observe the ferroelectric order in the unexplored R 2 BaCuO 5 (R = Er, Dy, Sm) series.…”

Field-induced spin reorientation transitions in antiferromagnetic ring-shaped spin chains

“…In the vicinity of or as a consequence of the phase transition, magnetic responses of AFMs can be modified. Indeed, entering the spin-flop phase reduces the potential barrier for magnetoelectric switching [12], enables long-distance spin-transport [13], enhances the skyrmion lifetime [14] and strengthens the magnetoelectric coupling [15]. These effects have been intensively studied for bulk AFMs, extended two-dimensional systems and straight spin chains [2].…”

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

“…The MD response can be also induced by the magnetoelastic coupling, e.g., in Co 4 Nb 2 O 9 , [ 6 ] Ba 3 NdRu 2 O 9 , [ 7 ] Sm 2 BaNiO 5 [ 8 ] and Pb 2 MnO 4 , [ 9 ] but the corresponding MD coefficient is still small. Despite that large MD response has been reported in some other families of materials such as La‐based double perovskites La 2 B MnO 6 ( B = Fe,Co,Ni), [ 10 ] rare‐earth sesquioxide Ce 2 O 3 , [ 11 ] brownmillerite compounds Ca 2 FeCoO 5 [ 12 ] and spin‐chain compound Tb 2 BaCoO 5 , [ 13 ] the MD effect in these compounds that is based on the spin order transitions usually occurs only at very low temperatures, [ 11b,14 ] or even is dominated by extrinsic effects. [ 15 ] As a consequence, achieving a large intrinsic MD response at room temperature is highly challengeable but quite desirable for electronic devices.…”