Magnetocaloric effect in melt-spun Laves phase intermetallic compound HoCo<inf>2</inf>

Magnetic and magnetocaloric properties of the melt-spun HoCo2 compound have been investigated. The sample orders ferrimagnetically at ∼94 K (TC). This is about 14 K larger than that of the TC reported for the arc-melted HoCo2 sample. This is found to be a second order transition whereas the arc-melted analogue is known to undergo a first order transition. Melt-spinning synthesis leads to micrograin formation in the sample. The maximum isothermal magnetic entropy change, ΔSmmax, near TC of the melt-spun HoCo2 is about −4.6 J kg−1 K−1 and −9.5 J kg−1 K−1 for 20 kOe and 50 kOe field changes, respectively. The corresponding refrigeration capacity and relative cooling power values are 115 J/kg and 148 J/kg for 20 kOe field change and 308 J/kg and 398 J/kg for 50 kOe field change. The relative cooling power is nearly equal to that of the arc-melted sample because the change of order of transition leads to broadening of ΔSm vs T curve. The increase in TC could be due to the enhanced ferromagnetic interactions present in the transition metal sublattice of the melt-spun HoCo2.