Structural and magnetic properties of MnCo1-xFexSi alloys

TL;DR

This study investigates how Fe substitution affects the structural and magnetic properties of MnCoSi alloys, revealing transitions from antiferromagnetic to ferromagnetic states and constructing a comprehensive phase diagram.

Contribution

It provides new insights into the magnetostructural phase transitions and magnetic behavior induced by Fe doping in MnCoSi alloys.

Findings

Fe doping decreases martensitic and Curie transition temperatures.

Fe induces a transition from spiral AFM to FM in martensite.

Metamagnetic transitions observed for certain Fe concentrations.

Abstract

The crystal structures, martensitic structural transitions and magnetic properties of MnCo1-xFexSi (0 <= x <= 0.50) alloys were studied by differential scanning calorimetry (DSC), x-ray powder diffraction (XRD) and magnetic measurements. In high-temperature paramagnetic state, the alloys undergo a martensitic structural transitions from the Ni2In-type hexagonal parent phase to the TiNiSi-type orthorhombic martensite. Both the martensitic transition temperature (TM) and Curie temperatures of martensite (T_C^M) decrease with increasing Fe content. The introduced Fe atoms establish ferromagnetic (FM) coupling between Fe-Mn atoms and destroy the double spiral antiferromagnetic (AFM) coupling in MnCoSi compound, resulting in a magnetic change in the martensite phase from a spiral AFM state to a FM state. For the alloys with x = 0.10, 0.15 and 0.20, a metamagnetic transition was observed in between the two magnetic states. A magnetostructural phase diagram of MnCo1-xFexSi (0 <= x <= 0.50) alloys was proposed.