Effect of composition on magnetocaloric properties of Mn3Ga(1−x)SnxC

Abstract

A study investigating the effect of Sn substitution on the magnetocaloric properties of Mn3Ga (1−x) SnxC compounds reveals that nature of the MCE has a strong dependence on the nature of the magnetic ordering. For small amounts of Sn (x ≤ 0.2) the MCE is of the inverse type wherein an increase in the applied field beyond 5T gives rise to a table like temperature dependence of the entropy due to a coupling between the first order FM -AFM transition and the field induced AFM -FM transition. Replacement of Ga by larger concentrations of Sn (x ≥ 0.71) (∆SM ) results in a change of the MCE to a conventional type with very little variation in the position of (∆SM )max with increasing magnetic field. This has been explained to be due to the local strain introduced by A site ions (Ga/Sn) which affect the magnetostructural coupling in these compounds.

Dynamics of nonergodic ferromagnetic/antiferromagnetic ordering and magnetocalorics in antiperovskite Mn3SnC

“…8(a) and 8(b). The maximum value S = 6 ± 0.4 J kg −1 K −1 is in agreement with those obtained for a similar sample from the Maxwell equations [18]. T (T ) calculated using c p (T ) is shown in Fig.…”

“…T ad of Mn 3 SnC is only about 0.4 K under 1.8-T field change, however, the virtue of this material is that it exhibits a magnetostructural transition at room temperature, so that if it were to be possible to alleviate AF exchange, the magnetocaloric effect could be enhanced. This could be possible by doping other elements in place of Sn as has been reported in a previous work [18]. The alleviation of AF exchange that could possibly exist in other known materials can be an important task for attaining better magnetocaloric materials.…”

“…Mn-based antiperovskite compounds also exhibit substantial magnetocaloric effects around their magnetostructural transitions with entropy changes, S, of about 80 mJ cm 3 K −1 under a magnetic-field change of 2 T [6,16,17]. Mn 3 SnC * mehmet.acet@uni-due.de compounds doped with other main group elements have been investigated for their magnetocaloric effects, and it was found that these materials can be appropriate for magnetic refrigeration [18]. However, in order to control and optimize magnetocaloric effects around first-order magnetostructural transitions, it is necessary to understand the details of the mechanism of the transition and any hysteresis effects associated with it.…”

Role of Tin and Carbon in the magnetic interactions in Mn3SnC

“…A competition between these two interactions can result in both, broad transition and a smaller entropy change. Further, studies on Mn 3 Ga 1−x Sn x C have shown that the strength of antiferromagnetic interactions are critically related to distortions of Mn 6 C octahedra or lattice strain and the effect of lattice strain can be seen in the variation of entropy peak as a function of magnetic field [19]. To check the effect of lattice strain in all the three samples, the change in peak temperature of entropy peak, ∆T = T peak (H) − T peak (0.1T ) is plotted as a function of applied field in the inset of Fig.…”

Absence of first order magnetic transition, a curious case of Mn3InC

“…An abrupt decrease in the shorter Mn -Mn distance at T ∼ 175 K results in an AFM ground state and gives rise to a large positive magnetic entropy change (∆S M ∼ 15 J/kg-K at 2 T, equivalent to an adiabatic temperature difference of 3 K) 9,13 . Introduction of Sn for Ga at the A-site results in a lattice expansion as well as a change in the nature of magnetocaloric effect from inverse to the conventional type with ∆S M is about −3 J/kg-K at 2 T applied field 14 . The larger size of Sn also seems to affect the distortions so as to cause the Mn 6 C octahedra to elongate along one direction and shrink along the other two.…”