Rare-earth based frustrated magnets have attracted great attention as excellent candidates for magnetic refrigeration at sub-Kelvin temperatures,while the experimental identification of systems exhibiting both large v...Rare-earth based frustrated magnets have attracted great attention as excellent candidates for magnetic refrigeration at sub-Kelvin temperatures,while the experimental identification of systems exhibiting both large volumetric cooling capacity and reduced working temperatures far below 1K remains a challenge.Here,through ultra-low temperature magnetism and thermodynamic characterizations,we unveil the large magnetocaloric effect(MCE)realized at sub-Kelvin temperatures in the frustrated Kagome antiferromagnet Gd_(3)BWO_(9)with T_(N)∼1.0 K.The isothermal magnetization curves indicate the existence of field(B)induced anisotropic magnetic phase diagrams,where four distinct magnetic phases for B‖c-axis and five magnetic phases for B‖ab-plane are identified at T<T_(N).The analysis of magnetic entropy S(B,T)data and direct adiabatic demagnetization tests reveal remarkable cooling performance at sub-Kelvin temperatures featured by a large volumetric entropy density of 502.2 mJ/K/cm^(3)and a low attainable minimal temperature T_(min)∼168mK from the initial cooling condition of 2K and 6 T,surpassing most Gd-based refrigerants previously documented in temperature ranges of 0.25–4 K.The realized T_(min)∼168mK far below T_(N)∼1.0K in Gd_(3)BWO_(9)is related to the combined effects of magnetic frustration and criticality-enhanced MCE,which together leave substantial magnetic entropy at reduced temperatures by enhancing spin fluctuations.展开更多
基金supported by the National Key Research and Development Program(Grant Nos.2024YFA1611200 and 2023YFA1406500)the National Natural Science Foundation of China(Grant Nos.12141002 and 52088101)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB1270000)。
文摘Rare-earth based frustrated magnets have attracted great attention as excellent candidates for magnetic refrigeration at sub-Kelvin temperatures,while the experimental identification of systems exhibiting both large volumetric cooling capacity and reduced working temperatures far below 1K remains a challenge.Here,through ultra-low temperature magnetism and thermodynamic characterizations,we unveil the large magnetocaloric effect(MCE)realized at sub-Kelvin temperatures in the frustrated Kagome antiferromagnet Gd_(3)BWO_(9)with T_(N)∼1.0 K.The isothermal magnetization curves indicate the existence of field(B)induced anisotropic magnetic phase diagrams,where four distinct magnetic phases for B‖c-axis and five magnetic phases for B‖ab-plane are identified at T<T_(N).The analysis of magnetic entropy S(B,T)data and direct adiabatic demagnetization tests reveal remarkable cooling performance at sub-Kelvin temperatures featured by a large volumetric entropy density of 502.2 mJ/K/cm^(3)and a low attainable minimal temperature T_(min)∼168mK from the initial cooling condition of 2K and 6 T,surpassing most Gd-based refrigerants previously documented in temperature ranges of 0.25–4 K.The realized T_(min)∼168mK far below T_(N)∼1.0K in Gd_(3)BWO_(9)is related to the combined effects of magnetic frustration and criticality-enhanced MCE,which together leave substantial magnetic entropy at reduced temperatures by enhancing spin fluctuations.
