We report a detailed study of the magnetic properties, critical analysis of magnetization, and magnetocaloric effect of a spin-2 kagome lattice ${\mathrm{YCa}}_3{\left(\mathrm{MnO}\right)}_3{\left({\mathrm{BO}}_3\right)}_4$. The experiments are complemented by the density functional band-structure calculations. The magnetic measurements suggest a highly frustrated nature of the compound due to competing ferro- and antiferromagnetic interactions, with the dominant one being ferromagnetic. It undergoes an unconventional ferromagnetic ordering at $T^{*}\simeq 7.8$ K and a field-induced metamagnetic transition in low fields, implying spin canting. A $H\text{−}T$ phase diagram is constructed that features three phase regimes. Indeed, the band-structure calculations reveal dominant ferromagnetic interaction along the chains that are coupled antiferromagnetically, yielding a frustrated kagome geometry. This compound shows a large magnetocaloric effect with isothermal entropy change $\mathrm{\Delta }{S}_m\simeq 12$ J/kg-K, adiabatic temperature change $\mathrm{\Delta }{T}_{\mathrm{ad}}\simeq 8.4$ K, and relative cooling power $\mathrm{RCP}\simeq 349$ J/kg for a field change of 7 T. The critical analysis of magnetization and magnetocaloric parameters suggests that the transition is a second-order phase transition and it is a tricritical mean-field type. Owing to its large magnetocaloric parameters, second-order phase transition, and no thermal hysteresis, ${\mathrm{YCa}}_3{\left(\mathrm{MnO}\right)}_3{\left({\mathrm{BO}}_3\right)}_4$ emerges as a potential rare-earth-free magnetic material for magnetic refrigeration.

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• Ferromagnetism
• Frustrated magnetism
• Magnetic interactions
• Magnetic phase transitions
• Magnetocaloric effect