Abstract
The magnetostructural coupling between structural and magnetic transitions leads to magneto-multifunctionalities of phase-transition alloys. Due to the increasing demands of multifunctional applications, to search for the new materials with tunable magnetostructural transformations in a large operating temperature range is important. In this work, we demonstrate that by chemically alloying MnNiSi with CoNiGe, the structural transformation temperature of MnNiSi (1200 K) is remarkably decreased by almost 1000 K. A tunable magnetostructural transformation between the paramagnetic hexagonal and ferromagnetic orthorhombic phase over a wide temperature window from 425 to 125 K is realized in (MnNiSi)1−x(CoNiGe)x system. The magnetic-field-induced magnetostructural transformation is accompanied by the high-performance magnetocaloric effect, proving that MnNiSi-CoNiGe system is a promising candidate for magnetic cooling refrigerant.
Highlights
Atoms, Tt of MnCoGe can be reduced from 420 K to below Curie temperature of the orthorhombic phase (TC) and Magnetostructural transformation (MST) from PM hexagonal to FM orthorhombic phase is realized during cooling[22,31]
It is reported that if Tt lies in the Curie-temperature window (CTW), which is the range between Curie temperatures of the hexagonal and orthorhombic phases[16,33,34], the structural transition will couple with magnetic state changes, bringing a large ΔM
In this (MnNiSi)1−x(CoNiGe)x system, Tt is successfully tuned down to below than TC, and the tunable MST between PM hexagonal and FM orthorhombic phase can be obtained in a large CTW by altering the CoNiGe-content
Summary
Atoms, Tt of MnCoGe can be reduced from 420 K to below Curie temperature of the orthorhombic phase (TC) and MST from PM hexagonal to FM orthorhombic phase is realized during cooling[22,31]. In the case of MnNiGe system, the stoichiometric tuning can reduce Tt from 470 K to below than 200 K and obtain MST from FM hexagonal to AFM orthorhombic phase with decreasing temperature[20]. The isostructural alloying opens up a new feasibility to realize the magnetostructural coupling in MnNiSi-based compounds[16,33,34,38,39,40,41]. By applying this method, the wide CTW can be further obtained. The effect is accompanied by a large magnetocaloric effect, indicating the potential applications in magnetic cooling refrigerator
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