Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userInvestigation of the tunnel magnetoresistance in junctions with a strontium stannate barrier
151
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We experimentally investigate the structural, magnetic and electrical transport properties of La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ based magnetic tunnel junctions with a SrSnO$_3$ barrier. Our results show that despite the large number of defects in the strontium stannate barrier, due to the large lattice mismatch, the observed tunnel magnetoresistance is comparable to tunnel junctions with a better lattice matched STiO$_3$ barrier, reaching values of up to 350% at T=5 K. Further analysis of the current-voltage characteristics of the junction and the bias voltage dependence of the observed tunnel magnetoresistance show a decrease of the TMR with increasing bias voltage. In addition, the observed TMR vanishes for T>200 K. Our results suggest that by employing a better lattice matched ferromagnetic electrode and thus reducing the structural defects in the strontium stannate barrier even larger TMR ratios might be possible in the future.
rate research
Read More
Using a simple quantum-mechanical model, we explore a tunneling anisotropic magnetoresistance (TAMR) effect in ferroelectric tunnel junctions (FTJs) with a ferromagnetic electrode and a ferroelectric barrier layer, which spontaneous polarization gives rise to the Rashba and Dresselhaus spin-orbit coupling (SOC). For realistic parameters of the model, we predict sizable TAMR measurable experimentally. For asymmetric FTJs, which electrodes have different work functions, the built-in electric field affects the SOC parameters and leads to TAMR dependent on ferroelectric polarization direction. The SOC change with polarization switching affects tunneling conductance, revealing a new mechanism of tunneling electroresistance (TER). These results demonstrate new functionalities of FTJs which can be explored experimentally and used in electronic devices.
We calculate the conductances and the tunneling magnetoresistance (TMR) of double magnetic tunnel junctions, taking as a model example junctions composed of Fe/ZnSe/Fe/ZnSe/Fe (001). The calculations are done as a function of the gate voltage applied to the in-between Fe layer slab. We find that the application of a gate voltage to the in-between Fe slab strongly affects the junctions TMR due to the tuning or untuning of conductance resonances mediated by quantum well states. The gate voltage allows a significant enhancement of the TMR, in a more controllable way than by changing the thickness of the in-between Fe slab. This effect may be useful in the design of future spintronic devices based on the TMR effect, requiring large and controllable TMR values.
We investigate the tunneling magnetoresistance in magnetic tunnel junctions (MTJs) comprised of Weyl semimetal contacts. We show that chirality-magnetization locking leads to a gigantic tunneling magnetoresistance ratio, an effect that does not rely on spin filtering by the tunnel barrier. Our results indicate that the conductance in the anti-parallel configuration is more sensitive to magnetization fluctuations than in MTJs with normal ferromagnets, and predicts a TMR as large as 10^4 % when realistic magnetization fluctuations are accounted for. In addition, we show that the Fermi arc states give rise to a non-monotonic dependence of conductance on the misalignment angle between the magnetizations of the two contacts.
We theoretically study the recently observed tunnel-barrier-enhanced dc voltage signals generated by magnetization precession in magnetic tunnel junctions. While the spin pumping is suppressed by the high tunneling impedance, two complimentary processes are predicted to result in a sizable voltage generation in ferromagnet (F)|insulator (I)|normal-metal (N) and F|I|F junctions, with one ferromagnet being resonantly excited. Magnetic dynamics in F|I|F systems induces a robust charge pumping, translating into voltage in open circuits. In addition, dynamics in a single ferromagnetic layer develops longitudinal spin accumulation inside the ferromagnet. A tunnel barrier then acts as a nonintrusive probe that converts the spin accumulation into a measurable voltage. Neither of the proposed mechanisms suffers from spin relaxation, which is typically fast on the scale of the exponentially slow tunneling rates. The longitudinal spin-accumulation buildup, however, is very sensitive to the phenomenological ingredients of the spin-relaxation picture.
We study interlayer exchange interaction in magnetic tunnel junctions with ferroelectric barrier. We focus on the influence of image forces on the voltage dependence of the interlayer magnetic interaction (magneto-electric effect). The influence of the image forces is twofold: 1) they significantly enforce magneto-electric effect occurring due to the surface charges at the interface between ferroelectric and ferromagnets; 2) in combination with voltage dependent dielectric constant of the ferroelectric barrier image forces cause an additional contribution to the magneto-electric effect in magnetic tunnel junctions. This contribution can exceed the one coming from surface charges. We compare the interlayer exchange coupling voltage variation with spin transfer torque effect and show that for half-metallic electrodes the interlayer exchange coupling variation is dominant and defines the magnetic state and dynamics of magnetization in the tunnel junction.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
