| Summary: | This paper contains a detailed study of low-field microwave absorption, which is observed in EMR spectra registered for a series of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>Ni</mi><mrow><mn>50</mn><mo>−</mo><mi mathvariant="normal">x</mi></mrow></msub><msub><mi>Co</mi><mi mathvariant="normal">x</mi></msub><msub><mi>Mn</mi><mrow><mn>35.5</mn></mrow></msub><msub><mi>In</mi><mrow><mn>14.5</mn></mrow></msub></mrow></semantics></math></inline-formula> (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">x</mi><mo>=</mo><mn>0</mn><mo>,</mo><mspace width="0.166667em"></mspace><mn>3</mn><mo>,</mo><mspace width="0.166667em"></mspace><mn>5</mn></mrow></semantics></math></inline-formula>) Heusler alloys polycrystalline in situ and annealed at 1173 K ribbons. The LFMA spectra for all ribbons were performed at X-band (∼9.5 GHz), at temperatures below Curie temperature. Additionally, for annealed <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>Ni</mi><mn>45</mn></msub><msub><mi>Co</mi><mn>5</mn></msub><msub><mi>Mn</mi><mrow><mn>35.5</mn></mrow></msub><msub><mi>In</mi><mrow><mn>14.5</mn></mrow></msub></mrow></semantics></math></inline-formula> ribbons, the LFMA signal dependencies of the external magnetic field modulation amplitude, modulation frequency, microwave power and microwave magnetic field phase were registered. These results confirm the resonant character of LFMA. To determine the basic EMR parameters, such as linewidth and resonance field, the experimental data were fitted by the Dyson function. The LFMA signal is satisfactorily matched by the two lines, and the variability of the component lines with temperature is remarkable.
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