Tuning the metamagnetic transition in the (Co, Fe)MnP system for magnetocaloric purposes

Abstract

The inverse magnetocaloric effect taking place at the antiferro-to-ferromagnetic transition of (Co,Fe)MnP phosphides has been characterised by magnetic and direct ΔT ad measurements. In Co 0.53 Fe 0.47 MnP, entropy change of 1.5 Jkg -1 K -1 and adiabatic temperature change of 0.6 K are found at room temperature for an intermediate field change (∆B= 1 T). Several methods were used to control the metamagnetic transition properties, in each case a peculiar splitting of the antiferro-to-ferromagnetic transition is observed.

Structural, magnetic and magnetocaloric properties of (Mn, Co)2(Si, P) compounds

“…In this temperature range, much higher ∆S maxima can be observed, even in materials based on second order transitions [1]. This limited inverse MCE is rather similar with recent works on MnM'X Co 2 P materials [20]. The maxima are lower than that of (Co,Fe)MnP, but this is mostly ascribable to an effect of the transition width.…”

“…In both cases, the common site preferences for these structures are used [11][12][13][14]21]. [20,21]. This thus suggests that the Si substitution on the non-metallic site affects the magneto-elastic coupling of Co 2 P-type materials in a way that is going beyond a simple size effect.…”

“…This is not surprising if one reconsiders that Co 2 P materials are actually constituted from the same blocks as Fe 2 P, a system known to have its structural and magnetic properties mostly driven by "electronic doping". In the previous work on the inverse MCE of MnM'X, the approach was mostly to vary the 3d elements [20]. In such a case, the geometrical and electronic factors work together [25].…”

“…Beside the silicide derived from MnCoSi, other series of alloys based on a different metalloid element also present this antiferro-ferromagnetic transition. Recent works have suggested that phosphides are a possibility [19,20]. Starting from MnCoP which is a ferromagnet with a relatively high saturation magnetization and Curie temperature (T C ≈ 600 K) [21], phosphorous has been substituted by silicon to increase the intermetallic distances and favour the appearance of an antiferromagnetic state at low temperature (i.e.…”

Origin of the magnetostructural coupling inFeMnP0.75Si0.25

“…Promising new directions toward finding well-performing MC materials are those focusing on materials with an antiferromagnetic (AFM) to FM metamagnetic phase transition [11][12][13][14][15][16]. Widely investigated representatives of this class of materials are the doped MnP-related P nma compounds [13,14].…”