paper

Large magnetocaloric effect in the kagome ferromagnet Li $_{9}$ Cr $_{3}$ (P $_{2}$ O $_{7}$ ) $_{3}$ (PO $_{4}$ ) $_{2}$

arXiv:2305.04744 · doi:10.1103/PhysRevApplied.18.054076

Abstract

Single-crystal growth, magnetic properties, and magnetocaloric effect of the $S = 3/2$ kagome ferromagnet Li $_{9}$ Cr $_{3}$ (P $_{2}$ O $_{7}$ ) $_{3}$ (PO $_{4}$ ) $_{2}$ (trigonal, space group: $P 3 ˉ c 1$ ) are reported. Magnetization data suggest dominant ferromagnetic intra-plane coupling with a weak anisotropy and the onset of ferromagnetic ordering at $T_{C} ≃ 2.6$ K. Microscopic analysis reveals a very small ratio of interlayer to intralayer ferromagnetic couplings ( $J_{⊥} / J ≃ 0.02$ ). Electron spin resonance data suggest the presence of short-range correlations above $T_{C}$ and confirms quasi-two-dimensional character of the spin system. A large magnetocaloric effect characterized by isothermal entropy change of $- I^ S_{m} ≃ 31$ J kg $^{- 1}$ K $^{- 1}$ and adiabatic temperature change of $- I^ T_{ad} ≃ 9$ K upon a field sweep of 7 T is observed around $T_{C}$ . This leads to a large relative cooling power of $R C P ≃ 284$ J kg $^{- 1}$ . The large magnetocaloric effect, together with negligible hysteresis render Li $_{9}$ Cr $_{3}$ (P $_{2}$ O $_{7}$ ) $_{3}$ (PO $_{4}$ ) $_{2}$ a promising material for magnetic refrigeration at low temperatures. The magnetocrystalline anisotropy constant $K ≃ - 7.42 \times 1 0^{4}$ erg cm $^{- 3}$ implies that the compound is an easy-plane type ferromagnet with the hard axis normal to the $ab$ -plane, consistent with the magnetization data.

13 pages, 14 figures

Large magnetocaloric effect in the kagome ferromagnet Li9​Cr3​(P2​O7​)3​(PO4​)2​

Abstract

Large magnetocaloric effect in the kagome ferromagnet Li $_{9}$ Cr $_{3}$ (P $_{2}$ O $_{7}$ ) $_{3}$ (PO $_{4}$ ) $_{2}$