Wide temperature span of entropy change in first-order metamagnetic MnCo_1−xFe_xSi

Abstract

Abstract. The crystal structure and magnetic properties of MnCo x Fe 1-x Si (x=0-0.5) compounds were investigated. With increasing Fe content, the unit cell changes anisotropically and the magnetic property evolves gradually: Curie temperature decreases continuously, the first-order metamagnetic transition from a low-temperature helical antiferromagnetic state to a high-temperature ferromagnetic state disappears gradually and then a spin-glass-like state and another antiferromagnetic state emerge in the low temperature region. The Curie transition leads to a moderate conventional entropy change. The metamagnetic transition not only yields a larger negative magnetocaloric effect at lower applied fields than in MnCoSi but also produces a very large temperature span (103 K for Δμ 0 H=5 T) of ∆ (T) , which results in a large refrigerant capacity. These phenomena were explained in terms of crystal structure change and magnetoelastic coupling mechanism. The low-cost MnCo 1-x Fe x Si compounds are promising candidates for near room temperature magnetic refrigeration applications because of the large isothermal entropy change and the wide working temperature span. PACS number(s): 75.30.Sg, 75.30.Kz IntroductionRecently, room-temperature magnetic refrigeration based on the magnetocaloric effect (MCE) has emerged as a competitive technology to gas compress for it is energy efficient and also environmentally friendly. Up to date, there are several candidate materials for magnetic refrigeration and according to the nature of the magnetic transition, they fall into two categories: first-order magnetic transition (FOMT) materials and second-order magnetic

Structural and magnetic properties of MnCo 1−x Fe x Si alloys

“…A magnetostructural phase diagram was proposed. During our studies, we noted a similar study on MnCo 1-x Fe x Si alloys has been published with an emphasis on the magnetocaloric effects [23]. Our present work provides a systematical study of the basic structural and magnetic behaviors in this alloy system.…”

Emergent evolution of first-order phase transitions from magneto-structural to magneto-elastic in MnCo1−y Fe y Ge1−x Si x alloys

“…In addition, the existence of non-collinear magnetic structures with a small spontaneous magnetic moment at 4.2 K for CoMnSi, confirmed by neutron diffraction measurements, has been proven [41]. For CoMnSi-based systems, containing CoMnSi 0.75 Ge 0.25 [41], MnCo 0.9 Ni 0.1 Si [42] and MnCo 1−x Fe x Si [36,43], a smaller d 1 results in an AFM state and a relatively larger d 1 facilitates an FM state. Thus, the AFM-FM transition with magneto-elastic coupling is sensitive to elemental components.…”

Influences of P doping on magnetic phase transition and structure in MnCoSi ribbon

“…The nearest-neighboring Mn-Mn distance [12] d 1 decreases from 2.985 Å for x = 0 to 2.929 Å for x = 0.5, while d 2 increases from 3.136 Å to 3.155 Å, which is opposite to the scenario in Fe-doped MnCoSi. [10] The reason is P substitutes for larger Si, while Fe substitutes for smaller Co, although they are on different sites. This difference can explain the difference in the magnetic properties between MnCoSi 1−x P x and MnCo 1−x Fe x Si and can also make the influence of the lattice on the magnetism clear.…”

“…[7] The influences of different dopings at Mn and Co sites on the MCE property and phase transition have already been investigated. [8][9][10] However, the influences of P substitution in the Si site on the crystal structure and magnetic properties have not been reported. In this paper, results of MnCoSi 1−x P x compounds are reported.…”