Large magnetocaloric effect in the frustrated antiferromagnet EuIr[formula omitted]P[formula omitted

Abstract

We present a theoretical analysis of the magnetocaloric effect in the frustrated antiferromagnet EuIr2P2. Monte Carlo simulations indicate a large magnetic entropy change ΔSMmax∼5 J kg−1 K−1 at T=2.45 K for a moderate change in the external magnetic field ΔB=1.2 Tesla. The highest value of ΔSM seems to be associated with the presence of a multicritical point in the magnetic field versus temperature phase diagram (at Bm∼1.2 Tesla and Tm∼2.2 K) but it persists with similar large values for a broad range of temperatures T≲Tm. Single crystal EuIr2P2 magnetization vs magnetic field experiments allowed us to obtain the magnetocaloric effect for T>2 K. The results are consistent with the theoretical analysis and show a large magnetocaloric effect for T∼2.5 K. Finally, we present a phenomenological Landau functional analysis that provides a simplified description of the phase diagram and of the magnetocaloric effect. Although the magnetic frustration in this system leads to a rich phase diagram, we found no clear indication that it plays a significant role enhancing the magneticaloric effect, other than by reducing the transition temperatures and fields.