Magnetic, transport and magnetocaloric properties in the Laves phase intermetallic Ho (Co1−xAlx)2 compounds

• The Al influence on magnetic properties of the Ho (Co1-xAlx)2 compounds is analyzed.
• The first-order magnetic transition appears in sample with Al concentrations x ≤ 0.06.
• The MCE and Curie temperature TC demonstrate complex Al concentration dependences.
• The magnetoresistance for sample with Al concentration x = 0.06 (58%) is maximum.
• High magnetic fields changes the Curie temperature Tc of the Ho (Co1−xAlx)2 compounds.

The magnetization, magnetoresistivity and magnetocaloric effect (MCE) of the Ho (Co1−xAlx)2Laves phase intermetallic compounds for x ⩽ 0.2 have been investigated. Complex measurements have been carried out in order to determine the influence of substitution in the Co sublattice by Al on the Co moment, type of the magnetic transition and related properties of these compounds. A comparative analysis of the magnetic, transport and magnetocaloric properties of Ho (Co1−xAlx)2 alloys under various Al concentration is represented. Substitutions at the Co site by Al are found to result in the appearance of itinerant electron metamagnetism (IEM) at the small Al concentrations and in positive magnetovolume effect, leading to an initial increase in the ordering temperature; on the other hand the magnetic phase transition temperature as well as ΔT (MCE) do not depend in direct way on the Al concentration. The 16% increase of magnetocaloric effect for the alloy with x = 0.02 is detected in relation to maternal HoCo2. A giant value of magnetoresistivity (58%) is observed for the alloy with the same Al concentration.