Formation and magnetic properties of spark plasma sintered Mn$_{3-\delta}$ ($\delta$ = 0, 1) alloys

Sonam Perween; A. Rathi; R. P. Singh; A. Bhattacharya; Parul Rani Raghuvanshi; P. V. Prakash Madduri; P. K. Rout; B. Sivaiah; Ajay Dhar; R. P. Pant; B. Gahtori; G. A. Basheed

arXiv · 1911.05040

Formation and magnetic properties of spark plasma sintered Mn$_{3-\delta}$ ($\delta$ = 0, 1) alloys

Sonam Perween·A. Rathi·R. P. Singh·A. Bhattacharya·Parul Rani Raghuvanshi·P. V. Prakash Madduri·P. K. Rout·B. Sivaiah·Ajay Dhar·R. P. Pant·B. Gahtori·G. A. Basheed

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Abstract

We present the synthesis of D0$_{22}$ Mn$_{3 - \delta}$Ga ($\delta$ = 0, 1) Heusler alloys by Spark Plasma Sintering method. The single phase Mn$_3$Ga (T$_\mathrm{c}$ $\simeq$ 780 K) is synthesized, while Mn$_2$Ga (T$_\mathrm{c}$ $\simeq$ 710 K) is found to coexist with a near-stoichiometric room temperature paramagnetic Mn$_9$Ga$_5$~($\approx$ 15 \%) phase due to its lower formation energy, as confirmed from our density functional theory (DFT) calculations. The alloys show hard magnetic behavior with large room temperature spontaneous magnetization m$_s$(80 kOe) = 1.63 (0.83) $\mu_\mathrm{B}$/f.u. and coercivity H$_\mathrm{c}$ = 4.28 (3.35) kOe for Mn$_3$Ga (Mn$_2$Ga). The magnetic properties are further investigated till T$_\mathrm{c}$ and the H$_\mathrm{c}$ (T) analysis by Stoner-Wohlfarth model shows the nucleation mechanism for the magnetization reversal. The experimental results are well supported by DFT calculations, which reveal that the ground state of D0$_{22}$ Mn$_2$Ga is achieved by the removal of Mn-atoms from full Heusler Mn$_3$Ga structure in accordance with half Heusler alloy picture.

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Sonam Perween, A. Rathi, R. P. Singh, A. Bhattacharya, Parul Rani Raghuvanshi, P. V. Prakash Madduri, P. K. Rout, B. Sivaiah, Ajay Dhar, R. P. Pant, B. Gahtori, G. A. Basheed. 2019-11-12. Formation and magnetic properties of spark plasma sintered Mn$_{3-\delta}$ ($\delta$ = 0, 1) alloys. https://arxiv.org/abs/1911.05040

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