Structure, Magnetocaloric Effect and Critical Behaviour in Ni50Mn30(Sn,In)20 Heusler Alloys

Abstract

A detailed investigation of structure, critical behaviour and magnetocaloric properties of Ni50Mn30Sn20 (Sn20) and Ni50Mn30In20 (In20) alloys has been investigated by means of Xrays diffraction and magnetic measurements. Ni50Mn30Sn20 alloy shows a cubic austenite 2 1 structure, and undergoes a second order magnetic transition at a Curie temperature of ,1 ( 20) = 333 . However, the Ni50Mn30In20 alloy exhibits a mixture of cubic 2 1 and 2 austenite structures having Curie temperatures of ,2 ( 20) = 285 and * ( 20) = 330 , respectively. The modified Arrott plots, Kouvel-Fisher curves and critical isotherm analysis have been used to estimate the critical exponents (, , and ) around the Curie temperature. For Sn20 alloy, the reliable exponents are consistent with the mean field model, revealing long-range ferromagnetic interactions. Nevertheless, the critical exponents of In20 alloy around 330 K cannot be arranged into any of the universality classes of well-known classical standard models. The maximum entropy change under 5 T of Sn20 (∆ = 2.43 . ) is slightly higher than that of In20 (∆ = 2.05 . ). The experimental results of entropy changes are in good agreement with those calculated using Landau theory.

Anomalous critical behavior and localized ferromagnetism of the half‐metallic double perovskite Sr2CrReO6

“… 47 The critical exponents of these two DPs are shown in Table 2. In fact, this happens for various magnetic materials 43,48–51 . In general, such unusual phenomenon is often related to magnetic disorder, magnetic inhomogeneities, and the presence of the Griffith phase 43,48,51 .…”

“…In fact, this happens for various magnetic materials. 43,[48][49][50][51] In general, such unusual phenomenon is often related to magnetic disorder, magnetic inhomogeneities, and the presence of the Griffith phase. 43,48,51 To clarify why the obtained exponents are inconsistent with common theoretical models, effective critical exponents in the asymptotic region need to be further investigated.…”

Hysteresis-free reversible magnetocaloric effect and critical behavior of Ni39.56Fe7.27Co2.97Mn40.65Sn9.55 full heusler alloy

“…Among all the above-mentioned materials, Ni-Mn-X (X = Sn, Sb, In, Ga) family depends on their composition and a minute change in composition can lead to significant effects. Although this family shows magneto-structural transformation most often, there have been many compositions which shows only magnetic transition [38][39][40]. It has been reported that, introduction of Co at the Ni site increases the ferromagnetic coupling, thus enhancing the MCE values in the process [41] and the brittleness of these alloys can be reduced significantly by substituting Fe at the Ni site, giving these materials mechanical stability [42,43].…”

Ni-Mn-Sn-Cu Alloys after Thermal Cycling: Thermal and Magnetic Response

“…Gd-based and Ni-Mn-In alloys are good candidates for magnetic refrigeration devices. Thus, Gd [12] or In [13] addition has been also analyzed. A minor amount of other metallic elements, such as Zn [14], Al [15] or Pd [16], or metalloids, such as B [17] have been also checked.…”