Investigation of the intrinsic magnetodielectric effect in La₂CoMnO₆: role of magnetic disorder

Abstract

We present a large magnetodielectric (MD) effect of 65% at 100 kHz with a 5 T field in a B-site ordered La 2 CoMnO 6 (LCMO) polycrystalline sample. Frequency and temperature dependent impedance and dielectric studies under a magnetic field divulge both intrinsic and extrinsic origins for the observed MD effect. The temperature dependent Raman spectroscopy measurement showed spin-lattice coupling that supports the intrinsic origin of the observed large MD response in LCMO. Extrinsic contributions to MD response mainly originate from disorder and interface effects; here, we signify this by hole carrier (Sr) doping at the A-site of the ordered LCMO sample. The comparison study has disclosed that with the disorder, the intrinsic polarization due to asymmetric hopping decreases significantly, and the disorder induced transport dominates in both MD and magnetoresistance behaviour with close resemblance.

Electrical transport properties and enhanced magnetoresistance effect in double perovskite La2–xCaxCoMnO6 (0 ≤ x ≤ 0.5)

“…. This result is consistent with the previous report . Still, the resistivities of the samples could partly explain that the smaller the porosity (with increasing x ), the smaller the resistivity.…”

Effect of strontium substitution on the structural and magnetic properties of La1.8Sr0.2MMnO6 (M = Ni, Co)-layered manganites

“…The hightemperature anomaly is Tc1~210 K, the medium-temperature anomaly locates at Tc2~150 K, and the low-temperature anomaly is Tc3~80 K. [30] The multiple magnetic phase transitions have been reported earlier for both La2CoMnO6 ceramics and thin films. [7,26,28,[51][52][53][54][55][56][57] In this case, due to the substitution of Sr a sharp transition was observed at 220±2 K. It is evident that temperature dependent ZFC and FC magnetization curves of LSNMO exhibit a sharp FM to PM transition at 160±2 K which is around 120 K less than that of parent LNMO. On the other hand, temperature dependence ZFC and FC cooled magnetization curves of LSCMO exhibit a sharp FM to PM transition at 220±2 K which is around 8 K less than that of parent LCMO.…”

“…It is reported that the temperature dependence ZFC and FC magnetization curves exhibit a sharp FM to PM transition at 230 K for parent LCMO. [26] It has also been found that depending on the synthesis conditions LCMO can also exhibit one and more magnetic transitions. LCMO shows two FM transitions occurring at Tc1~220 K and Tc2~150 K. [52] Besides, other researchers reported that three distinct anomalies can be observed in both FC and ZFC curves of LCMO.…”

“…It was also observed that the positions of the peaks comply with the reported values in La1.8Sr0.2NiMnO6 [24,25] and La1.8Sr0.2CoMnO6 manganites. [26] Earlier, the unsubstituted polycrystalline La2MMnO6 (M = Ni, Co) sample has revealed a monoclinic structure. [26,[27][28] The lattice parameters calculated from the patterns are displayed in Table 1.…”

“…[26] Earlier, the unsubstituted polycrystalline La2MMnO6 (M = Ni, Co) sample has revealed a monoclinic structure. [26,[27][28] The lattice parameters calculated from the patterns are displayed in Table 1. From the Table 1, it is seen that lattice parameters of 'a' and 'b' in La2MMnO6 (M = Ni, Co) and La1.8Sr0.2MMnO6 (M = Ni, Co) manganites are almost same, but lattice parameter 'c'is changed due to the 10% Sr substitution in La sites of La1.8Sr0.2MMnO6 (M = Ni, Co) manganites.…”