X-ray photoelectron spectroscopy analysis as a tool to assess factors influencing magnetic anisotropy type in Co/MgO system with gold interlayer

X-ray photoelectron spectroscopy (XPS) studies of Au/Co/Au(0.3 nm)/MgO and Au/Co/MgO systems were conducted in order to monitor the electronic structure modification at Co/MgO interface with/without gold interlayer. A detailed analysis of Co 2p states revealed that the amount of minor oxygen contribution at Co/MgO interface decreased after the Au interlayer was added. The obtained XPS results together with density functional theory (DFT) allowed explanation of the increase of surface anisotropy energy in the sample with the gold interlayer in terms of (i) noble and transitional metal d-d orbital hybridization; (ii) interfacial Co 3d and O 2p; and (iii) interface imperfectio

The structure and stability of beta-Ta thin films

Ta films with tetragonal crystalline structure (beta-phase), deposited by magnetron sputtering on different substrates (steel, silicon and silicon dioxide), have been studied. In all cases, very highly preferred (001) orientation was observed in x-ray diffraction (XRD) measurements. All diffraction data revealed two weak reflections corresponding to d-spacing of 0.5272 and 0.1777 nm. The presence of the two peaks, attributed to (001) and (003) reflections, indicates that beta-Ta films exhibit a high preference for the space group of P-421m over P42/mnm, previously proposed for beta-Ta. Differences in relative intensities of (00l) reflections, calculated for single crystal beta-Ta sigma-type Frank-Kasper structure and those measured in the films, are attributed to defects in the films. Molecular dynamics simulations performed on tantalum clusters with six different initial configurations using the embedded-atom-method (EAM) potential revealed the stability of beta-Ta, which might explain its growth on many substrates under various deposition conditions.Comment: 27 pages, 6 figures,1 tabl

Cryogenic temperature growth of Sn thin films on ferromagnetic Co(0001)

Topological electronic materials hold great promise for revolutionizing spintronics, owing to their topological protected, spin-polarized conduction edge or surface state. One of the key bottlenecks for the practical use of common binary and ternary topological insulator (TI) materials is the large defect concentration which leads a high background carrier concentration. Elemental tin in its α-phase is a room temperature topological semimetal, which is intrinsically less prone to defect-related shortcomings. Recently, the growth of ultrathin α-Sn films on ferromagnetic Co surfaces has been achieved, however, thicker films are needed to reach the 3D topological Dirac semimetallic state. Here, the growth of α-Sn films on Co at cryogenic temperatures was explored. Very low-temperature growth holds the promise of suppressing undesired phases, alloying across the interfaces, as well as the formation of Sn pillars or hillocks. Nevertheless, the critical Sn layer thickness of ∼3 atomic layers, above which the film partially transforms into the undesired β-phase, remains the same as for room-temperature growth. From ferromagnetic resonance studies, and supported by electron microscopy, it can be concluded that for cryogenic Sn layer growth, the interface between Sn and Co remains sharp and the magnetic properties of the Co layer stay intact

Terahertz Transients Emitted from La-Sr-Mn-O/Metal Nanobilayers Excited by Femtosecond Optical Pulses

We report on the generation of electromagnetic transients of picosecond duration from La-Sr-Mn-O/Au and La-Sr-Mn-O/lr nanobilayers, illuminated by femtosecond laser pulses in the presence of an external magnetic field. Fourier analysis revealed that the frequency content of these transients extended up 4 THz. The amplitude of THz transients followed the functional dependence of La-Sr-Mn-O magnetization on the magnetic field and was also tunable by varying the intensity of the optical pulses. We ascribe the observed emission of THz transients to the inverse spin Hall effect, earlier demonstrated in metallic ferromagnet/metal spintronic nanobilayers

Terahertz Transients Emitted from La-Sr-Mn-O|Metal Nanobilayers Excited by Femtosecond Optical Pulses

We report on the generation of electromagnetic transients of picosecond duration from La-Sr-Mn-O/Au and La-Sr-Mn-O/lr nanobilayers, illuminated by femtosecond laser pulses in the presence of an external magnetic field. Fourier analysis revealed that the frequency content of these transients extended up 4 THz. The amplitude of THz transients followed the functional dependence of La-Sr-Mn-O magnetization on the magnetic field and was also tunable by varying the intensity of the optical pulses. We ascribe the observed emission of THz transients to the inverse spin Hall effect, earlier demonstrated in metallic ferromagnet/metal spintronic nanobilayers

Onset-Time Control of THz Transients Generated by Spintronic Emitters

We have generated intense electromagnetic transients by femtosecond laser pulse illumination of ferromagnet/metal (F/M) nanobilayers, in the presence of an external magnetic field. Fourier analysis revealed that the frequency content of these transients extended up to ~5 THz. We have also observed that upon the increase of the magnetic field, the entire THz transient shifts towards earlier times by up to 110 fs. We ascribe this magnetically tunable onset-time shift to extra acceleration of photoelectrons induced due to the Lorenz force

Onset-Time Control of THz Transients Generated By Spintronic Emitters

We have generated intense electromagnetic transients by femtosecond laser pulse illumination of ferromagnet/metal (F/M) nanobilayers, in the presence of an external magnetic field. Fourier analysis revealed that the frequency content of these transients extended up to ~5 THz. We have also observed that upon the increase of the magnetic field, the entire THz transient shifts towards earlier times by up to 110 fs. We ascribe this magnetically tunable onset-time shift to extra acceleration of photoelectrons induced due to the Lorenz force