The role of the metal-oxide interface in determining spin polarization electrons tunneling from or into ferromagnetic transition metals magnetic tunnel junctions is reported. cobalt with an alumina barrier positive, but it negative when strontium titanate cerium lanthanite. results are ascribed to bonding effects at metal-barrier interface. influence electronic structure interfaces on raises interesting fundamental problems and opens new ways optimize magnetoresistance junctions.

We report tunnel magnetoresistance (TMR) measurements on $\mathrm{Co}/{\mathrm{SrTiO}}_{3}/{\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ junctions. The half-metallic ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ electrode is used as a spin analyzer. large $(\ensuremath{-}50%)$ inverse TMR indicates negative polarization of Co, in agreement with the density states (DOS) $d$ band Co. bias dependence TMR, maximum at $\ensuremath{-}0.4\mathrm{V}$ and crossover to normal...

Magnetic interactions involving ferromagnetic layers separated by an insulating barrier have been studied experimentally on a fully epitaxial hard-soft magnetic tunnel junction: Fe/MgO/Fe/Co. For thickness below 1 nm, clear antiferromagnetic interaction is observed. Moreover, when reducing the MgO from to 0.5 coupling strength increases up J=-0.26 erg.cm(-2). This behavior, well fitted theoretical models, provides unambiguous signature of interlayer exchange spin-polarized quantum tunneling.

We report on the fabrication and properties of (cobalt/alumina/iron oxide) tunnel junctions. observe magnetoresistance (MR) effects reaching 43% at 4.2 K 13% room temperature. This large MR is ascribed to presence a Fe3−xO4 (close half-metallic magnetite) phase identified by electron diffraction. At low temperature, drops sharply when bias voltage smaller than 10 mV, which suggests that originates from activation tunneling channels through spin polarized states below above Fermi level in iron oxide.

Magnetization manipulation in the absence of an external magnetic field is a topic great interest, since many novel physical phenomena need to be understood and promising new applications can imagined. Cutting-edge experiments have shown capability switch magnetization thin films using ultrashort polarized laser pulses. In 2007, it was first observed that switching for GdFeCo alloy helicity-dependent later helicity-independent also demonstrated on same material. Recently, all-optical has...

Magnetic frustration effects in artificial kagome arrays of nanomagnets are investigated using x-ray photoemission electron microscopy and Monte Carlo simulations. Spin configurations demagnetized networks reveal unambiguous signatures long range, dipolar interaction between the nanomagnets. As soon as system enters spin ice manifold, model captures observed physics, while short range fails.

Abstract Geometrical frustration in magnetic materials often gives rise to exotic, low-temperature states of matter, such as the ones observed spin ices. Here we report imaging a thermally active artificial ice that reveal fingerprints fragmentation process. This corresponds splitting degree freedom into two channels and is evidenced both real reciprocal space. Furthermore, internal organization interpreted within framework hybrid spin–charge model directly emerges from parent kagome dipolar...

Using specially engineered structures to tailor the optical absorption in a metallic multilayer, we analyze magnetization dynamics of $\mathrm{Co}/\mathrm{Pt}$ multilayer buried below thick Cu layer. We demonstrate that hot electrons alone can very efficiently induce ultrafast demagnetization. Simulations based on electron ballistic transport implemented within microscopic model accounts for local dissipation angular momentum nicely reproduce experimental results, ruling out contribution...

We report on spin-polarized tunneling in fully epitaxial Fe/MgO/Fe/Co tunnel junctions. By increasing the thickness of insulating layer (tMgO), we have strongly enhanced magnetoresistance. Values up to ∼100% at 80 K (∼67% room temperature) been observed with tMgO=2.5 nm. This magnetoresistance ratio, which is much larger than one predicted by Jullière’s model, can be understood framework ab initio calculations.

Single-crystalline V/Fe(0.7 nm)/MgO(1.2nm)/Fe(20 nm) magnetic tunnel junctions are studied to quantify the influence of an electric field on Fe/MgO interface anisotropy. The thinnest Fe soft layer has a perpendicular anisotropy (PMA), whereas thickest acts as sensor for changes. When electrons added at PMA (negative voltage), no changes observed. For positive voltage, constant decreases with increasing bias voltage. A huge 1150 fJ V−1 m−1 variation is observed and magnetization found turn...

Transparent nanoscale-film heterojunctions based on Cu2O and ZnO were fabricated by atomic layer deposition reactive magnetron sputtering. The constitutive layers exhibit high crystalline quality a local epitaxial relation between was achieved with [110] || [001] [010] as evidenced resolution transmission electron microscopy and. films show very low resistivity mobility values of 9–150 Ω cm 19 cm2/V s, respectively. Cu2O/ZnO nonlinear rectifying behavior characteristic p–n junction,...

A brief theoretical review points out the specific aspects of electronic transport in single-crystal magnetic tunnel junctions employing bcc(100) Fe electrodes and a MgO(100) insulating barrier. The predictions are compared to experimental reality both equilibrium out-of-equilibrium regimes. For extremely small MgO thickness, we illustrate that Fe/MgO/Fe systems leads antiferromagnetic interactions. Artificial based on coupling by spin polarized tunnelling have been elaborated studied. In...

We report experimental evidence of thermal effects on the displacement vortex walls in NiFe nanostrips. With use nanosecond current pulses, a unidirectional motion magnetic domain towards hotter part nanostrips is observed, addition to current-induced wall motion. By tuning heat dissipation samples and modeling diffusion, we conclude that this can only be explained by presence temperature profile along nanostrip. A quantitative analysis experiments shows that, top classical thermodynamic...

In combining spin- and symmetry-resolved photoemission, magnetotransport measurements ab initio calculations we detangled the electronic states involved in transport Fe(1-x)Co(x)(001)/MgO/Fe(1-x)Co(x)(001) magnetic tunnel junctions. Contrary to previous theoretical predictions, observe a large reduction TMR (from 530 200% at 20 K) for Co content above 25 atomic% as well anomalies conductance curves. We demonstrate that these unexpected behaviors originate from minority spin state with Δ(1)...

We present an experimental study of all-optical helicity-dependent switching (AO-HDS) ferromagnetic Pt/Co/Pt heterostructures with perpendicular magnetic anisotropy. The sample is patterned into a Hall cross and the AO-HDS measured via anomalous effect. This all-electrical probing magnetization during enables statistical quantification ratio for different laser parameters, such as threshold power to achieve exposure time needed reach complete at given power. find that cumulative process,...

Devices employing surface acoustic waves (SAWs) are of major interest in sensor applications, due to their ease manufacturing, sensitivity, small size, and wireless interrogation. This study shows that the response a magnetic SAW device is much more complex than as often reported, detailed understanding its properties essential controlling magnetoacoustic response. For example, sensing can be extended out-of-plane fields, beyond traditional in-plane measurements.

Single Co/Al2O3/NiFe and double Co/Al2O3/Co/Al2O3/NiFe planar tunnel junctions were grown by sputtering subsequently patterned in a four-step process using optical lithography. The Al2O3 barriers are formed radio frequency plasma oxidation of 1.5 nm aluminum layers. exhibit three clear resistance levels depending on the relative configuration magnetizations. Both single maximum magnetoresistance (MR) ratios above 10% at room temperature 20% 30 K decrease MR with increasing bias voltage. With...

We have developed a new original technique to study the magnetization reversal dynamics of thin films with element selectivity in nanosecond time scale. X-ray magnetic circular dichroism measurements pump-probe mode are carried out taking advantage structure synchrotron radiation. The each layers complex heterostructures (like spin valves or tunnel junctions) can be probed independently. interlayer coupling studied systems has been shown play key role determination individual layer.

In ${\mathrm{Gd}}_{40}{\mathrm{Fe}}_{60}/{\mathrm{Tb}}_{12}{\mathrm{Fe}}_{88}$ exchange-coupled bilayer system, both negative and positive exchange bias, depending on cooling field, are observed. A full enlightenment of the magnetic configurations adopted by system is obtained through micromagnetic calculations in agreement with magnetization susceptibility measurements. Magnetization shifts bias fields then quantitatively correlated to presence a frozen interface domain wall. This model may...

We report on the experimental observation of tunneling across an ultrathin metallic Cr spacer layer that is inserted at interface a Fe/MgO/Fe(001) junction. show how this remarkable behavior in solid-state device reflects quenching transmission particular electronic states, as expected from symmetry-filtering properties MgO barrier and band structure bcc Cr(001) epitaxial junction stack. This can promote quantum well states adjacent Fe layer.

A magnetic tunnel junction sensor is proposed, with both the detection and reference layers pinned by IrMn. Using differences in blocking temperatures of IrMn films different thicknesses, crossed anisotropies can be induced between electrodes. The pinning sensing electrode ensures a linear reversible output. It also allows tuning sensitivity range sensor. authors show that varies linearly ferromagnetic thickness electrode. demonstrated an increased leads to rise reduction operating range.

We fabricated a perpendicularly magnetized bit pattern media using hexagonally close-packed auto-assembled anodic alumina template with 100 nm and 50 periods by depositing Co/Pt multilayer to form an ordered array of ferromagnetic nanodots, so-called nanobumps. used Hall resistance measurements magnetic force microscopy characterize the dot-by-dot magnetization reversal mechanism under applied field. The role interdot exchange coupling dipolar are investigated. Then we focus on separating...

Tb-Co ferrimagnetic alloy thin films and spin valves have been grown to study their magnetoresistance response in various geometries. The studied alloys show strong perpendicular anisotropy tunable magnetization by several orders of magnitude. Magnetoresistance signals such as giant (GMR), anisotropic (AMR), extraordinary Hall effect (EHE), magnon (MMR) studied. angular dependence those magnetoresistive effects is also investigated. Finally we demonstrate that adjusting the layer composition...