Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userAntiferromagnetic Coupling between Surface and Bulk Magnetization and Anomalous Magnetic Transport in Electro-deposited Co Film
258
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report an interesting magnetic behavior of a Co film (thickness ~ 350 {AA}) grown on Si/Ti/Cu buffer layer by electro-deposition (ED) technique. Using depth sensitive X-ray reflectivity and polarized neutron reflectivity (PNR) we observed two layer structures for the Co film grown by ED with a surface layer (thickness ~ 100 {AA}) of reduced density (~ 68% of bulk) compared to rest of the Co film (thickness ~ 250 {AA}). The two layer structure is consistent with the histogram profile obtained from atomic force microscope (AFM) of the film. Interestingly, using PNR, we found that the magnetization in the surface Co layer is inversely (antiferomagnetically) coupled (negative magnetization for surface Co layer) with the rest of the Co layer for the ED grown film. While we compare PNR result for a Co film of similar layered structure grown by sputtering, the film showed a uniform magnetization as expected. We also show that the depth dependent unusual magnetic behavior of ED grown Co film may be responsible for anomalous anisotropic magnetoresistance observed in low field in this film as compared to the Co film grown by sputtering. Combining X-ray scattering, AFM, superconducting quantum interface device magnetometry (SQUID), PNR and magneto-transport measurements we attempted to correlate and compare the structural, magnetic and morphological properties with magneto-transport of Co films grown by ED and sputtering. The study indicates that the interesting surface magnetic property and magneto-transport property of the ED film is caused by its unique surface morphology.
rate research
Read More
We have investigated the magnetoelectric and magnetodielectric response in FeVO$_4$, which exhibits a change in magnetic structure coincident with ferroelectric ordering at $T_{N2}$$approx$15 K. Using symmetry considerations, we construct a model for the possible magnetoelectric coupling in this system, and present a discussion of the allowed spin structures in FeVO$_4$. Based on this model, in which the spontaneous polarization is caused by a trilinear spin-phonon interaction, we experimentally explore the magnetoelectric coupling in FeVO$_4$ thin films through measurements of the electric field induced shift of the multiferroic phase transition temperature, which exhibits an increase of 0.25 K in an applied field of 4 MV/m. The strong spin-charge coupling in fvo, is also reflected in the significant magnetodielectric shift, which is present in the paramagnetic phase due to a quartic spin-phonon interaction and shows a marked enhancement with the onset of magnetic order which we attribute to the trilinear spin-phonon interaction. We observe a clear magnetic field induced dielectric anomaly at lower temperatures, distinct from the sharp peak associated with the multiferroic transition, which we tentatively assign to a spin reorientation cross-over. We also present a magnetoelectric phase diagram for FeVO$_4$.
Inducing magnetic orders in a topological insulator (TI) to break its time reversal symmetry has been predicted to reveal many exotic topological quantum phenomena. The manipulation of magnetic orders in a TI layer can play a key role in harnessing these quantum phenomena towards technological applications. Here we fabricated a thin magnetic TI film on an antiferromagnetic (AFM) insulator Cr2O3 layer and found that the magnetic moments of the magnetic TI layer and the surface spins of the Cr2O3 layers favor interfacial AFM coupling. Field cooling studies show a crossover from negative to positive exchange bias clarifying the competition between the interfacial AFM coupling energy and the Zeeman energy in the AFM insulator layer. The interfacial exchange coupling also enhances the Curie temperature of the magnetic TI layer. The unique interfacial AFM alignment in magnetic TI on AFM insulator heterostructures opens a new route toward manipulating the interplay between topological states and magnetic orders in spin-engineered heterostructures, facilitating the exploration of proof-of-concept TI-based spintronic and electronic devices with multi-functionality and low power consumption.
The structural and magnetic properties of a series of superlattices consisting of two ferromagnetic metals La$_{0.7}$Sr$_{0.3}$MnO$_3$ (LSMO) and SrRuO$_3$ (SRO) grown on (001) oriented SrTiO$_3$ are studied. Superlattices with a fixed LSMO layer thickness of 20 unit cells (u.c.) and varying SRO layer thickness show a sudden drop in magnetization on cooling through temperature where both LSMO and SRO layers are ferromagnetic. This behavior suggests an antiferromagnetic coupling between the layers. In addition, the samples having thinner SRO layers (n TEXTsymbol{<} 6) exhibit enhanced saturation magnetization at 10 K. These observations are attributed to the possible modification in the stereochemistry of the Ru and Mn ions in the interfacial region.
We present a detailed study of the interface morphology of an electro-deposited (ED) Ni/Cu bilayer film by using off-specular (diffuse) neutron reflectivity technique and Atomic Force Microscopy (AFM). The Ni/Cu bilayer has been electro-deposited on seed layers of Ti/Cu. These two seed layers were deposited by magnetron sputtering. The depth profile of density in the sample has been obtained from specular neutron reflectivity data. AFM image of the air-film interface shows that the surface is covered by globular islands of different sizes. The AFM height distribution of the surface clearly shows two peaks [Fig. 3] and the relief structure (islands) on the surface in the film can be treated as a quasi-two-level random rough surface structure. We have demonstrated that the detailed morphology of air-film interfaces, the quasi-two level surface structure as well as morphology of the buried interfaces can be obtained from off-specular neutron reflectivity data. We have shown from AFM and off-specular neutron reflectivity data that the morphologies of electro-deposited surface is distinctly different from that of sputter-deposited interface in this sample. To the best of our knowledge this is the first attempt to microscopically quantify the differences in morphologies of metallic interfaces deposited by two different techniques viz. electro-deposition and sputtering.
The interface between organic semiconductor [OSC]/ferromagnetic [FM] material can exhibit ferromagnetism due to their orbital hybridization. Charge/spin transfer may occur from FM to OSC layer leading to the formation of `spinterface i.e. the interface exhibiting a finite magnetic moment. In this work, the magnetic properties of Co/C$_{60}$ bilayer thin film have been studied to probe the interface between Co and C$_{60}$ layer. Polarized neutron reflectivity [PNR] measurement indicates that the thickness and moment of the spinterface are $sim$ 2 $pm$ 0.18 nm and 0.8 $pm$ 0.2 $mu_B$/cage, respectively. The comparison of the magnetization reversal between the Co/C$_{60}$ bilayer and the parent single layer Co thin film reveals that spinterface modifies the domain microstructure. Further, the anisotropy of the bilayer system shows a significant enhancement ($sim$ two times) in comparison to its single layer counterpart which is probably due to an additional interfacial anisotropy arising from the orbital hybridization at the Co/C$_{60}$ interface.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
