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<p>The present experimental study investigates the magnetic ground state and spin fluctuation behavior of Ni₉₂TM₈ (TM = Cr, Nb) alloys through detailed magnetization measurements and theoretical analysis using Self-Consistent Renormalization (SCR) and Takahashi’s spin fluctuation theories. The alloys were synthesized via vacuum arc melting and subsequently characterized using energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM), confirming single-phase formation with compositional homogeneity. Temperature and field dependent magnetization (M–T and M–H) measurements reveal second-order ferromagnetic transitions with Curie temperatures of 168&#xa0;K (Ni₉₂Cr₈) and 173&#xa0;K (Ni₉₂Nb₈). Both alloys exhibit spontaneous magnetic moments (0.18 μ<sub>B</sub>/f.u and 0.21 μ<sub>B</sub>/f.u) and large Rhodes–Wohlfarth ratios, characteristic of weak itinerant ferromagnetism (WIFM). The temperature dependence of spontaneous magnetization follows M<sup>2</sup> ∝ T<sup>2</sup> at low temperatures and M<sup>2</sup> ∝ T<sup>4/3</sup> near T<sub>C</sub>, in agreement with SCR predictions. Analysis based on Takahashi’s theory yields spin fluctuation parameters (T₀, T<sub>A</sub>, F₁₀) consistent with values reported for classical WIFMs such as ZrZn₂ and Ni₃Al, confirming dominant spin fluctuation effects. Deviations from linearity in Arrott plots near T<sub>C</sub> and the linearity of M<sup>4</sup> vs H/M plots substantiate the itinerant nature of magnetism. The findings elucidate Ni₉₂Cr₈ and Ni₉₂Nb₈ within the weak itinerant regime, governed by delocalized electron magnetism and strong spin fluctuations, offering potential for spintronic and quantum phase transition studies.</p>

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Experimental Investigation of Spin Fluctuation and Weak Itinerant Ferromagnetism in Ni₉₂TM₈ (TM = Cr, Nb) Alloys

  • 期刊论文

  • 发表日期：

    2025年12月15日

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  • Sonu Vishvakarma,
  • Alok Singh

摘要

The present experimental study investigates the magnetic ground state and spin fluctuation behavior of Ni₉₂TM₈ (TM = Cr, Nb) alloys through detailed magnetization measurements and theoretical analysis using Self-Consistent Renormalization (SCR) and Takahashi’s spin fluctuation theories. The alloys were synthesized via vacuum arc melting and subsequently characterized using energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM), confirming single-phase formation with compositional homogeneity. Temperature and field dependent magnetization (M–T and M–H) measurements reveal second-order ferromagnetic transitions with Curie temperatures of 168 K (Ni₉₂Cr₈) and 173 K (Ni₉₂Nb₈). Both alloys exhibit spontaneous magnetic moments (0.18 μB/f.u and 0.21 μB/f.u) and large Rhodes–Wohlfarth ratios, characteristic of weak itinerant ferromagnetism (WIFM). The temperature dependence of spontaneous magnetization follows M2 ∝ T2 at low temperatures and M2 ∝ T4/3 near TC, in agreement with SCR predictions. Analysis based on Takahashi’s theory yields spin fluctuation parameters (T₀, TA, F₁₀) consistent with values reported for classical WIFMs such as ZrZn₂ and Ni₃Al, confirming dominant spin fluctuation effects. Deviations from linearity in Arrott plots near TC and the linearity of M4 vs H/M plots substantiate the itinerant nature of magnetism. The findings elucidate Ni₉₂Cr₈ and Ni₉₂Nb₈ within the weak itinerant regime, governed by delocalized electron magnetism and strong spin fluctuations, offering potential for spintronic and quantum phase transition studies.