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Molecular beam epitaxy is widely used for engineering low-dimensional materials. Here, we present a novel extension of the capabilities of this method by assisting epitaxial growth with the presence of an external magnetic field (MF). MF-assisted epitaxial growth was implemented under ultra-high vacuum conditions thanks to specialized sample holders for generating in-plane or out-of-plane MF and dedicated manipulator stations with heating and cooling options. The significant impact of MF on the magnetic properties was shown for ultra-thin epitaxial magnetite films grown on MgO(111). Using in situ and ex situ characterization methods, scanning tunneling microscopy, conversion electron Mössbauer spectroscopy, and the magneto-optic Kerr effect, we showed that the in-plane MF applied during the reactive deposition of 10 nm Fe3O4(111)/MgO(111) heterostructures influenced the growth morphology of the magnetite films, which affects both in-plane and out-of-plane characteristics of the magnetization process. The observed changes are explained in terms of modification of the effective magnetic anisotropy. [ABSTRACT FROM AUTHOR]

Large‐area antimony telluride (Sb2Te3) thin films are grown by a metal organic chemical vapor deposition technique on 4" Si(111) substrates, and their topological character probed by magnetoconductance measurements. When interfaced with Fe thin films, broadband ferromagnetic resonance spectroscopy (BFMR) shows a clear increase of the damping parameter in Fe/Sb2Te3 when compared to a reference Fe layer, which may suggest the occurrence of spin pumping (SP) into Sb2Te3. Simultaneously, X‐ray reflectivity and conversion electron Mossbauer spectroscopy evidence the development of a chemically and magnetically pure Fe/Sb2Te3 interface. However, by conducting SP‐FMR, it is shown that no spin‐to‐charge conversion (S2C) occurs in Fe/Sb2Te3, while a clear SP signal develops by introducing a 5 nm Au interlayer between Fe and Sb2Te3, with a measured inverse Edelstein effect conversion efficiency of λIEE = 0.27 nm. The results shed some light on the correlation among the chemical‐structural‐magnetic properties of the Fe/Sb2Te3 interface, the broadening of the magnetic damping parameter as detected by BFMR, and the occurrence of S2C, as probed by SP‐FMR. [ABSTRACT FROM AUTHOR]

Fe-Gd amorphous thin films of different compositions and thicknesses were analyzed with respect to their magnetic and magneto-optical behavior. By preparing samples with the same Fe/Gd elemental ratio at different thicknesses, and of various Fe/Gd ratios at constant thickness, respectively, we were able to show the influences of these two parameters on the interconnected behavior of the two magnetic sub-lattices, one of Fe and the other of Gd, which are antiferromagnetically coupled. Magneto-Optical Kerr Effect (MOKE) measurements revealed reversed hysteresis loops for sample compositions crossing the magnetic compensation point. Temperature dependent magnetization curves highlighted the variation of the overall net contribution of the two magnetic sub-lattices by changing either the Fe/Gd elemental ratio or the film thickness. 57Fe Conversion Electron Mössbauer (CEM) spectra give additional support to the specific magnetic behavior evidenced by temperature and field dependent Superconducting Quantum Interference Device (SQUID) magnetometry. [ABSTRACT FROM AUTHOR]

The present work reports the study of transcritical state of magnetic anisotropy in FexNi100-x films as a function of film thickness and composition. The transcritical state is a manifestation of weak perpendicular magnetic anisotropy resulting in peculiar hysteresis loop and stripe magnetic domains above a critical thickness of film. Signatures of transcritical state, corroborated by the formation of stripe domains, are observed in the magneto optical Kerr effect(MOKE) data and magnetic force microscopy (MFM) data of FexNi100-x films with ≈ 75 nm thickness for x = 7. The effect of thickness on the formation of transcritical state is studied for Fe9Ni91 films and it is observed that films with thickness ≥ 105 nm exhibit transcritical state. Further a quantitative analysis of magnetic texture is carried out by 57Fe conversion electron Mössbauer spectroscopy (CEMS) measurements for the thickness variation samples. The CEMS data show a systematic variation in the area ratio of second and third line intensity as a function of thickness corroborating the MOKE data. The films are studied as a function of thermal annealing and it is observed that the transcritical state still preserved for Fe9Ni91 films of higher thickness even after annealing at 300 ∘C. [ABSTRACT FROM AUTHOR]

The effect of the implantation of 57Fe ions with an energy of 1 MeV and fluence of 5 × 1016 ion/cm2 on the properties of structural materials used in the nuclear industry (metallic Ta and Mo and 12Cr18N10T stainless steel) is studied using 57Fe Mössbauer spectroscopy and X-ray diffraction. The concentration of implanted Fe atoms is calculated using the SRIM program. The formation of two phases is found in Ta and Mo. The main phase in molybdenum (84%) is a solid solution of Fe substitution in Mo. The main phase in tantalum (78%) corresponds to Fe-cluster formation in a Ta matrix. Apparently, additional surface phases are related to the formation of Fe + Ta/Mo + vacancy clusters in the areas of grain boundaries, or are associated with areas of partial amorphization of the material. [ABSTRACT FROM AUTHOR]

We have implanted ZnO thin film with 40 keV Fe+ ions to a high fluence of 1.25 × 1017 ions/cm2. Elemental and magnetic phase compositions were investigated by XRD, XPS, CEMS, and VSM methods. The Fe-implanted ZnO film reveals strong ferromagnetism at room temperature. The implanted iron ions are found in different valence states of Fe2+ and Fe3+. It was attributed to the formation of paramagnetic and ferromagnetic iron-based phases. The ferromagnetism is explained with the formation of a magnetic ordered solution of iron ions in ZnO matrix. Post-implantation annealing in a high vacuum results in the decrease of magnetism due to the formation of magnetite nanoparticles. Unlabelled Image • Elemental and magnetic phase compositions of ZnO thin film implanted with 40 keV Fe+ ions to a high fluence of 1.25 × 1017 ions/cm2 have been studied by using XRD, XPS and Mossbauer spectroscopy; • The as-implanted film shows room temperature ferromagnetism attributed to magnetically ordering of Fe3+ ions in cationic sites of ZnO lattice; • Magnetic system of Fe-ions solid solution is unstable and relaxes with the formation of magnetite nanoparticles in ZnO film during thermal annealing in vacuum. [ABSTRACT FROM AUTHOR]

In order to enable the use of the prototypical 2D‐layered MoS2 for spintronics, its integration with ferromagnetic layers is mandatory. By employing interface‐sensitive 57Fe conversion electron Mössbauer spectroscopy (CEMS), hard X‐ray photoelectron spectroscopy (HAXPES), and transmission electron microscopy (TEM), the chemical, structural, and magnetic properties of the Fe/2D‐MoS2 interface are investigated. CEMS shows that out of the first 1 nm of Fe in direct contact with 2D‐MoS2, about half of the Fe atoms keeps the un‐perturbed Fe local environment, partly in regions where the original 2D‐layered structure of MoS2 is preserved as shown by TEM. The remaining reacting Fe atoms exclusively bond with Mo, with the majority of them being characterized by a ferromagnetic environment and the rest coordinating in a paramagnetic Fe‐Mo configuration. The preferential Fe bonding with Mo is corroborated by HAXPES analysis. The results provide detailed insight into the link between the bonding configuration and the interfacial magnetism at the Fe/2D‐MoS2 heterojunction. [ABSTRACT FROM AUTHOR]

Conversion electron Mössbauer spectroscopy (CEMS) is a surface-sensitive technique because of the shallowness of the escape depth of conversion electrons. The proportional counter with the sample built-in is usually used for CEMS with a flow of He mixed with a quenching gas. This flow-type proportional counter with a mixed gas, however, is not suited to high-temperature measurements. For high-temperature operation, we fabricated a sealed-off proportional counter operated above 850 K for CEMS, which is filled with pure He at a pressure of 1-8 × 10 Pa. The distribution of the output pulse voltage revealed an inflection point suggesting that two multiplication mechanisms are operative. The multiplication factor of the proportional counter was estimated to be about 10-10. By means of the fabricated proportional counter, we investigated the magnetic phase transition of FeO, whose Curie temperature is 858 K. We successfully observed the ferromagnetic-paramagnetic phase transition without the reduction of the sample. [ABSTRACT FROM AUTHOR]