Influence of orbital two-channel Kondo effect on anomalous Hall effect in ferrimagnetic composites of LaNiO₃ and CoFe₂O₄

Abstract

In this report, we have investigated the magnetoresistance (MR) and Hall effect of the ferrimagnetic composites containing LaNiO 3 and CoFe 2 O 4 (CFO) (with CFO content 15% and 20%) which exhibit orbital two-channel Kondo (2CK) effect and therefore pronounced resistivity upturn at low temperature. Both composites manifest a negative to positive crossover in MR with increasing temperature. The MR is described by the Khosla and Fisher model of spin fluctuations scattering of conduction electrons and the two-band theory based on hybridized p-d sub-bands. The Hall resistivity of the composites consists of both ordinary and anomalous part. The negative sign of the ordinary Hall coefficient suggests electrons as the dominating charge carriers. The coefficient of anomalous Hall resistivity ( R S ) follows the scaling relation ( R S = aρ xx + bρ 2 xx ) with longitudinal resistivity (ρ xx ) at high temperature above the resistivity upturn. However, at low temperature R S shows non-monotonous behaviour and deviates from the scaling relation where orbital 2CK effect takes place. More detailed study below the resistivity upturn of the composite with 20% CFO reveals that this deviation occurs around the Kondo temperature. This breakdown of scaling relation around the Kondo temperature indicates the possible influence of orbital 2CK on the anomalous Hall effect.

Effect of LaNiO3 on the impedance and dielectric properties of CoFe2O4: a high temperature study

“…The advantage of tuning the properties by varying compositions have made the composites very popular materials in the field of multiferroics [1,2], superconductivity [3,4] or to improve mechanical and thermal properties [5] or magneto transport properties [6,7]. In our recent work, we have shown that the structural defects of the composites containing LaNiO 3 (LNO) and CoFe 2 O 4 (CFO) dominate the charge transport properties when the amount of the defects is increased after a certain level which leads to the orbital two-channel Kondo effect [8,9]. This motivates us to correlate the electrical properties with the micro-structure of the composite materials.…”