arXiv subjects

Rantej Bali

Publications and source records attributed to Rantej Bali.

4 recordsLinked to original sources

arXiv2026

High Throughput Analysis of Nanobeam Electron Diffraction Datasets using Unsupervised Clustering

If disk detection is applied to nanobeam electron diffraction datasets, then the results are effectively a list of vectors describing the position of every diffraction peak in real and reciprocal space. This is the natural territory for the application of clustering algorithms, and they are shown to be highly effective at decomposing such datasets and automating imaging and analysis. Examples are shown in both polycrystalline and single crystal (with precipitates) systems. Additionally, automated separation of amorphous or deeply nanocrystalline components is also found to be possible allowing composite images of both amorphous and crystalline components in partially crystallised samples to be easily and automatically generated. These advances promise to increase throughput in atomic structure analysis with nanobeam diffraction, and also make finding minor components much easier. They can also serve as a preliminary step towards more detailed crystallographic or crystal size/shape distribution analysis.

cond-mat.mtrl-sci↗

arXiv2021

Spin polarization and magnetotransport properties of systematically disordered $\mathrm{Fe}_{60}\mathrm{Al}_{40}$ thin films

We investigate the evolution of spin polarization, spontaneous Hall angle (SHA), saturation magnetization and Curie temperature of $B2$-ordered Fe$_{60}$Al$_{40}$ thin films under varying antisite disorder, induced by Ne$^{+}$-ion irradiation. The spin polarization increases monotonically as a function of ion fluence. A relatively high polarization of 46 % and the SHA of 3.1 % are achieved on 40 nm thick films irradiated with 2 $\cdot$ 10$^{16}$ ions/cm$^2$ at 30 keV. An interesting divergence in the trends of the magnetization and SHA is observed for low disorder concentrations. The high spin polarization and its broad tunability range make ion-irradiated Fe$_{60}$Al$_{40}$ a promising material for application in spin electronic devices.

cond-mat.mtrl-sci↗

arXiv2019

Magnetic response of FeRh to static and dynamic disorder

Changes of the magnetic and crystal structure on the microscopic scale in 40 nm FeRh thin films have been applied to investigate the phenomena of a disorder induced ferromagnetism at room temperature initiated through light ion-irradiation with fluences up to 0.125 Ne$^+$/nm$^{-2}$. Magnetometry shows an increase of magnetic ordering at low temperatures and a decrease of the transition temperature combined with a broadening of the hysteresis with rising ion fluence. $^{57}$Fe Mössbauer spectroscopy reveals the occurrence of an additional magnetic contributions with an hyperfine splitting of 27.2 T - identical to that of ferromagnetic B2-FeRh. The appearance of an anti-site Fe-contribution can be assumed to be lower than 0.6 Fe-at%, indicating that no change of the chemical composition is evident. The investigation of the local structure shows an increase of the static mean square relative displacement determined by X-ray absorption fine structure spectroscopy, while an increase of the defect-concentration has been determined by positron annihilation spectroscopy. From the changes of the microscopic magnetic structure a similarity between the temperature induced and the structural disorder induced ferromagnetic phase can be observed. These findings emphasize the relationship between magnetic ordering and the microscopic defect structure in FeRh.

cond-mat.mtrl-sci↗

arXiv2019

Magneto-structural correlations in a systematically disordered B2 lattice

Ferromagnetism in certain B2 ordered alloys such as Fe$_{60}$Al$_{40}$ can be switched on, and tuned, via antisite disordering of the atomic arrangement. The disordering is accompanied by a $\sim$1 % increase in the lattice parameter. Here we performed a systematic disordering of B2 Fe$_{60}$Al$_{40}$ thin films, and obtained correlations between the order parameter ($S$), lattice parameter ($a_0$), and the induced saturation magnetization ($M_{s}$). As the lattice is gradually disordered, a critical point occurs at 1-$S$=0.6 and $a_0$=291 pm, where a sharp increase of the $M_{s}$ is observed. DFT calculations suggest that below the critical point the system magnetically behaves as it would still be fully ordered, whereas above, it is largely the increase of $a_0$ in the disordered state that determines the $M_{s}$. The insights obtained here can be useful for achieving tailored magnetic properties in alloys through disordering.

cond-mat.mtrl-sci↗