Spin-lattice coupling mediated giant magnetodielectricity across the spin reorientation in Ca2FeCoO5

Abstract

The structural, phonon, magnetic, dielectric, and magneto dielectric responses of the pure bulk Brownmillerite compound Ca2FeCoO5 are reported. This compound showed giant magneto dielectric response (10%-24%) induced by strong spin-lattice coupling across its spin reorientation transition (150-250 K). The role of two Debye temperatures pertaining to differently coordinated sites in the dielectric relaxations is established. The positive giant magneto-dielectricity is shown to be a direct consequence of the modulations in the lattice degrees of freedom through applied external field across the spin reorientation transition. Our study illustrates novel control of magneto-dielectricity by tuning the spin reorientation transition in a material that possess strong spin lattice coupling.

Observation of magnetoelastic and magnetoelectric coupling in Sc doped BaFe12O19 due to spin-glass-like phase

“…All Raman spectra were fitted using the Lorentzian function and fitting of the most prominent modes is shown in an inset of figure 10(a around the ~50 K (T max ) transition. This is a direct indication of the existence of strong magnetoelastic coupling in the system, as found in other materials [87][88][89]. As A 1g mode is related to the vibration of Fe-O bonds in FeO 5 bypiramid and FeO 6 octahedra, the anomalous behaviour in these modes affects the bond lengths which, in all probability, drive the modulation in lattice around T max and can induce ferroelectricity in the system through the inverse Dzyalonshinskii-Moriya mechanism as found in GdMnO 3 [90].…”

Roles of Re-entrant cluster glass state and spin–lattice coupling in magneto–dielectric behavior of giant dielectric double perovskite La1.8Pr0.2CoFeO6

“…A small negative MD is observed for low temperature region (25-80 K) with maximum (−0.42%) at 50 K. At high temperature region (125-275 K), maximum ∼−4% MD is found at 200 K. The observation of such MDE in particular LPCFO is astonishing as no MDE has been reported in both parent compounds (LCFO and PCFO). In literature, the contribution of some major factors have been suggested in magneto-dielectric effect, including magneto-resistance (MR) [44], magneto-striction [45], spin pair correlation [46], spin lattice coupling [47,48], electromagnon scattering [49], polaron mechanism [50], and dipole relaxation [51]. In the present case, the negative MD at low temperature (LT) can be explained by presence of reentrant cluster glass in this material.…”

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

“…The large MD response has been observed in several materials, such as DyMnO 3 (500%, 18 K, 3.8 T), [ 24 ] Ca 2 FeCoO 5 (24%, 220 K, 5 T), [ 12 ] DyMn 2 O 5 (109%, 3 K, 7 T), [ 25 ] and Ce 2 O 3 (200%, 6.1 K, 8 T). [ 11b ] However, the MD response in these materials usually occurs under high applied magnetic fields or at temperatures far below the room temperature.…”

“…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.…”