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Manganites have shown potential in spintronics because they exhibit high spin polarization. Here, by ferromagnetic resonance we have studied the damping properties of La0.67Sr0.33MnO3/Pt bilayers which are prepared by oxide molecular beam epitaxy. The damping coefficient (α) of a La0.67Sr0.33MnO3 (LSMO) single layer is found to be 0.0104. However the LSMO/Pt bilayers exhibit a decrease in α with an increase in Pt thickness. This decrease in the value of α is probably due to high anti-damping like torque. Furthermore, we have investigated the angle dependent inverse spin Hall effect (ISHE) to quantify the spin pumping voltage from other spin rectification effects such as the anomalous Hall effect and anisotropic magnetoresistance. We have observed a high spin pumping voltage (∼20 μV). The results indicate that both anti-damping and spin pumping phenomena occur simultaneously.

Ferromagnetic materials exhibiting low magnetic damping (α) and moderately high-saturation magnetization are required from the viewpoints of generation, transmission, and detection of spin waves. Since spin-to-charge conversion efficiency is another important parameter, high spin mixing conductance $$({g_{r}^{\uparrow \downarrow}})$$ ( g r ↑ ↓ ) is the key for efficient spin-to-charge conversion. Full Heusler alloys, e.g., Co2Fe0.4Mn0.6Si (CFMS), which are predicted to be 100% spin-polarized, exhibit low α. However, $$g_r^{ \uparrow \downarrow }$$ g r ↑ ↓ at the interface between CFMS and a paramagnet is not fully understood. Here, we report investigations of spin pumping and the inverse spin Hall effect in CFMS/Pt bilayers. Damping analysis indicates the presence of significant spin pumping at the interface of CFMS and Pt, which is also confirmed by the detection of an inverse spin Hall voltage. We show that in CFMS/Pt, $$g_r^{ \uparrow \downarrow }$$ g r ↑ ↓ (1.70 × 1020 m−2) and the interface transparency (83%) are higher than the values reported for other ferromagnetic/heavy metal systems. We observed a spin Hall angle of ~0.026 for the CFMS/Pt bilayer system.

High spin to charge conversion efficiency is the requirement for the spintronics devices which is governed by spin pumping and inverse spin Hall effect (ISHE). In last one decade, ISHE and spin pumping are heavily investigated in ferromagnet/ heavy metal (HM) heterostructures. Recently antiferromagnetic (AFM) materials are found to be good replacement of HMs because AFMs exhibit terahertz spin dynamics, high spin-orbit coupling, and absence of stray field. In this context we have performed the ISHE in CoFeB/ IrMn heterostructures. Spin pumping study is carried out for $Co_{40}Fe_{40}B_{20} (12\ nm)/ Cu (3\ nm)/ Ir_{50}Mn_{50} (t\ nm)/ AlO_{x} (3\ nm)$ samples where \textit{t} value varies from 0 to 10 nm. Damping of all the samples are higher than the single layer CoFeB which indicates that spin pumping due to IrMn is the underneath mechanism. Further the spin pumping in the samples are confirmed by angle dependent ISHE measurements. We have also disentangled other spin rectifications effects and found that the spin pumping is dominant in all the samples. From the ISHE analysis the real part of spin mixing conductance (\textit{$g_{r}^{\uparrow \downarrow}$}) is found to be 0.704 $\pm$ 0.003 $\times$ $10^{18}$ $m^{-2}$.

This article reports exchange bias (EB) and memory effect in nanocrystalline CoCr2O4 with a detailed understanding of the origin of the observed effect. In order to investigate the EB effect in nanocrystalline CoCr2O4, two samples are synthesized with particle sizes 12 and 7 nm via sol-gel route (the second one is embedded in amorphous silica host). For both the samples, despite usual core-shell interaction or ‘surface’ domination, conventional EB effect is observed where the EB field sharply decreases with temperature and vanishes over the spiral ordering temperature (TS) of the samples. A bulk sample of the same composition, with particle size greater than 150 nm, reproducing similar characteristics, rules out the origin of EB due to surface effect. Results indicate that the exchange bias is due to inherent magnetic inhomogeneity: interaction between spiral spin order and collinear ferrimagnetic order below TS. The ac-susceptibility measurement points towards absence of surface glassiness in the sample with 12 nm particle size. However, the sample with particle size 7 nm reveals the characteristics of superspin-glass (SSG), confirmed by magnetic memory effects both in time (t) and temperature (T) dependent magnetization protocols.