First-order ferromagnetic transition in single-crystalline (Mn,Fe)2(P,Si)

TL;DR

This study reports the successful growth and characterization of (Mn,Fe)2(P,Si) single crystals, revealing a first-order ferromagnetic transition with soft magnetic properties suitable for magnetic refrigeration.

Contribution

First demonstration of single-crystalline (Mn,Fe)2(P,Si) with detailed structural and magnetic analysis, highlighting its first-order transition and magnetic anisotropy.

Findings

Crystals exhibit a first-order ferromagnetic transition at Curie temperature.

Magnetic anisotropy is weak, indicating soft magnetic behavior.

Discontinuous magnetization jumps occur below TC and are reversible with cycling.

Abstract

(Mn,Fe)2(P,Si) single crystals have been successfully grown by flux method. Single crystal diffraction demonstrates that Mn0.83Fe1.17P0.72Si0.28 crystallizes in a hexagonal crystal structure (space group P-62m) at both 100 and 280 K, in the ferromagnetic and paramagnetic states, respectively. The magnetization measurements show that the crystals display a first-order ferromagnetic phase transition at their Curie temperature (TC). The preferred magnetization direction in is along the c axis. A weak magnetic anisotropy of K1 = 0.25x106 J/m3 and K2 = 0.19x106 J/m3 is found at 5 K. These values indicate a soft magnetic behaviour favourable for magnetic refrigeration. A series of discontinuous magnetization jumps is observed far below TC by increasing the field at a constant temperature. These magnetization jumps are irreversible, occur spontaneously at constant temperature and magnetic field, but can be restored by cycling across the first-order phase transition.