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Ferromagnetic single crystalline MnNiSi samples were first fabricated through a Sn-flux growth technique, followed by measurements of their structural characteristics and intrinsic magnetic properties. Additionally, the critical behavior for second-order ferromagnetic to paramagnetic phase transition was investigated through utilization of techniques such as the modified Arrott plot, the Kouvel–Fisher method, and the magnetocaloric effect scaling law method. Through different methods of analysis, reliable critical exponents were obtained. Renormalization of interactions around the Curie temperature indicates the reliability of the obtained exponents. The obtained critical exponents are close to those theoretically predicted for a three-dimensional isotropic short-range Heisenberg ferromagnet but shift toward the long-range mean-field estimates. This may arise from the coupling of short- and long-range interactions as well as the competition between localized Mn–Mn magnetic interactions and the hybridization between p- and d-type orbitals. [ABSTRACT FROM AUTHOR]

Spin gapless semiconductor (SGS) has attracted much attention since its theoretical prediction, while concrete experimental hints are still lacking in the relevant Heusler alloys. Here in this work, by preparing the series alloys of Mn2CoGa1−xAlx (x = 0, 0.25, 0.5, 0.75, and 1), we identified the vanishing of the anomalous Hall effect in the ferromagnetic Mn2CoGa (or x = 0.25) alloy in a wide temperature interval, accompanying with growing contribution from the ordinary Hall effect. As a result, comparatively low carrier density (1020 cm−3) and high carrier mobility (150 cm2/V s) are obtained in the Mn2CoGa (or x = 0.25) alloy in the temperature range of 10–200 K. These also lead to a large dip in the related magnetoresistance at low fields. However, in a high Al content, although the magnetization behavior is not altered significantly, the Hall resistivity is, instead, dominated by the anomalous one, just analogous to that widely reported in Mn2CoAl. The distinct electrical-transport behavior of x = 0 and x = 0.75 (or 1) is presently understood by their possible different scattering mechanism of the anomalous Hall effect due to the differences in the atomic order and conductivity. Our work can expand the existing understanding of the SGS properties and offer a better SGS candidate with higher carrier mobility that can facilitate the application in the spin-injected related devices. [ABSTRACT FROM AUTHOR]

Spin‐gapless semiconductors (SGS) are highly attractive for spintronics applications due to their unique spin‐polarized band structure. In this study, the potential SGS candidate of Mn2CoGa alloy is focused on by growing thin films using magnetron sputtering on Si(001)/SiO2 substrates. By applying appropriate heat treatment, the Mn2CoGa thin films can crystallize into the expected Heusler structure, as confirmed by the dominant (220) peak observed in X‐ray diffraction. These films exhibit soft magnetized behavior, with a saturation magnetization of approximately 1.86 μBf.u.−1 at 10 K. This value deviates slightly from the theoretical prediction, indicating the presence of antisite disorder within the film. The resistivity curve shows a negative temperature coefficient, which is attributed to the strong electron–electron interaction that is also connected to the disorder. Despite the presence of disorder, positive variation and sign reversal of the magnetoresistance are observed, along with a nearly vanishing anomalous Hall effect, both of which are typical characteristics of SGS. Compared to bulk Mn2CoGa, the carrier concentration is larger and the mobility is lower in the film, while similar temperature dependences are observed. [ABSTRACT FROM AUTHOR]