Heated dot magnetic recording (HDMR) provides a path to increase the areal density of magnetic recording media beyond 4 Tb/in². HDMR-based recording media requires ultrasmall, noninteracting, and thermally stable magnetic dots with high perpendicular anisotropy. We have synthesized nonstoichiometric Fe₆₀Pt₄₀ nanoclusters with and without a Pt buffer layer on silicon substrates, which shows a reduction in chemical ordering temperatures. The Fe₆₀Pt₄₀ nanoclusters retain the hard magnetic phase up to 1023 K with the coercive field of 1.3 Tesla due to the Pt element compensation from the buffer layer. This compensation of Pt was confirmed through X-ray diffraction (XRD) investigations where two distinct phases of Fe₃Pt and FePt₃ are observed at elevated annealing temperatures. Micromagnetic simulations were performed to understand the effect of magnetic anisotropy, dipolar interaction, and exchange coupling between the soft magnetic Fe₃Pt and hard magnetic FePt. The results imply that nonstoichiometric Fe₆₀Pt₄₀ with the Pt buffer layer facilitates low chemical ordering temperatures retaining the high perpendicular anisotropy with minimal noninteracting behavior, suitable for HDMR.

Realizing atomically flat interfaces between the ultrathin perovskite oxides is a challenging task, which usually possess different chemical environments, depending on the terminating lattice planes. Hence, tuning the interfaces across the heterostructures for desired electrical and magnetic properties is a powerful approach in oxide electronics. Focusing on these aspects, in the present work we employ a novel strategy of engineering the interfaces through the layer stacking sequence and degree of strain to probe the changes occurring in the local atomic environment at the interfaces, magnetic behaviour, and electronic properties of ferromagnetic bilayers La0.7Sr0.3MnO3 (LSMO)/LaCoO3 (LCO) grown by the pulsed laser deposition technique. The biaxial tensile strain experienced by these layers drives the ferromagnetic (FM) ordering temperatures to lower values as compared to their bulk counterparts. Interestingly, the bilayer sequence LCO (15 nm)/LSMO (5 nm) (BL2) exhibits large magnetocrystalline anisotropy (Ku ≈ 4.7 × 104 erg/cc) and weak anti-FM coupling across the interface of the two FM constituents, resulting in a partial compensation in the magnetic moment of the system within a specific temperature window (ΔT = 184 − 82 K). However, for T ≤ 82 K, the FM superexchange interaction between the trivalent Co high-spin and low-spin states dominates the overall magnetic ordering in BL2. The magnetodynamic features probed by the frequency dependent FM resonance (FMR) on this system yield the gyromagnetic ratio (γ/2π ∼ 29.22 GHz/T), demagnetization fields (4πMeff ∼ 3770 Oe), and effective damping constant (αeff ∼ 0.0143) for the BL2 configuration. Moreover, the strength of the nearest-neighbor exchange interaction Jeff in the BL2 configuration exhibits linear falloff with the increasing LCO layer thickness (2 nm ≤𝑡𝐿𝐶𝑂≤ 18 nm). This scenario is also consistent with the variation of the effective number of spins available per unit volume [10 cm−3 ≤ NV(×1022) ≤ 2 cm−3] with increasing tLCO. As tLCO approaches negligibly small values (<2 nm), the magnitude of Jeff/kB reaches its maximum ∼5.47 K (for LCO) and 21.93 K (for LSMO), which is in good agreement with Jeff/kB ∼ 5 ± 2 K (20 ± 2 K) for highly epitaxial LCO (LSMO) single layers. These results demonstrate that the layer sequence control of magnetic coupling across the interfaces opens a constructive approach for exploring the novel electronic devices

Herein, the effect of microstructure on the electronic, and superconducting properties of niobium mononitride (NbN) thin films grown using a high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (dcMS) is studied. X-ray reflectivity, cross-sectional scanning electron microscopy and atomic force microscopy measurements suggest that the film grown with dcMS has a non-uniform distribution of islands with loosely packed columns while the HiPIMS grown film has a smoother surface and a denser microstructure. Although the X-ray diffraction measurements show a single-phase rock-salt-type crystal structure in both cases, the local and electronic structure analyzed using N K-edge X-ray absorption near edge structure measurements reveals the evidence of a large amount of Nb vacancies in dcMS-NbN while HiPIMS-NbN film is closer to stoichiometry. The ordered structure of HiPIMS-NbN sample results in a relatively higher superconducting transition temperature of 15.2?K and lower normal state resistivity of 90????cm with a moderate critical field of 18?T and smaller coherence length of 4.2?nm. These results suggest HiPIMS can be utilized to grow high-quality superconducting thin films of few nanometers required in modern technological devices such as single-photon detectors, superconducting quantum interference devices.

Present study provides an insight of tailoring magnetic properties (static and dynamic) driven by structural modifications, with controlled incorporation of Ta in soft magnetic CoFeB films. Unlike conventional thermal annealing, stress induced in-plane uniaxial magnetic anisotropy of CoFeB have observed to be release with incorporation of Ta, as confirmed from in-plane rotation dependent magneto-optical Kerr effect (MOKE). Increasing atomic percent of Ta in CoFeB is accompanied with decreasing saturation magnetization of soft-magnetic layer and film densification, as confirmed from polarized neutron and X-ray reflectivities. Ferromagnetic resonance (FMR) confirms the reduction of effective magnetization of the samples with Ta incorporation, with rise of damping parameter because of increasing magnetic inhomogenities. Further, the effect of vacuum annealing on these films has been investigated. Post annealing measurements suggest rapid elimination of magnetic anisotropy for Ta doped CoFeB films. Annealing at a temperature beyond CoFeB crystallization temperature results in an increase of magnetization, relative to as-prepared samples, amplitude of which modifies with incorporated Ta concentration. Such enhancement is accompanied with the structural changes as confirmed from X-ray diffraction (XRD) measurements, resulting an increase of magnetic coercivity. The results are important in view of tailoring the functional properties of CoFeB films for wide range of applications.