Cerium-based intermetallics are currently attracting much interest as a possible alternative to existing high-performance magnets containing scarce heavy rare-earth elements. However, the intrinsic magnetic properties of Ce in these systems are poorly understood due to the difficulty of a quantitative description of the Kondo effect, a many-body phenomenon where conduction electrons screen out the Ce-4f moment. Here, we show that the Ce-4f shell in Ce–Fe intermetallics is partially Kondo screened. The Kondo scale is dramatically enhanced by nitrogen interstitials suppressing the Ce-4f contribution to the magnetic anisotropy, in striking contrast to the effect of nitrogenation in isostructural intermetallics containing other rare-earth elements. We determine the full temperature dependence of the Ce-4f single-ion anisotropy and show that even unscreened Ce-4f moments contribute little to the room-temperature intrinsic magnetic hardness. Our study thus establishes fundamental constraints on the potential of cerium-based permanent magnet intermetallics.

铈基金属间化合物作为可能包含现有稀有重稀土元素的高性能磁体的替代品，目前引起了广泛的关注。但是，由于难以定量描述近藤效应，即在多体现象中传导电子屏蔽了Ce-4 f矩，因此对这些系统中Ce的固有磁性能了解甚少。在这里，我们证明了Ce -Fe金属间化合物中的Ce-4 f壳已部分经过Kondo筛选。氮间隙物抑制Ce-4 f可以显着提高Kondo规模与含有其他稀土元素的同构金属间化合物中的氮化作用形成鲜明对比的是，它对磁各向异性有贡献。我们确定了Ce-4 f单离子各向异性的全温度依赖性，并表明，即使未经筛选的Ce-4 f矩对室温固有磁硬度的贡献也很小。因此，我们的研究建立了对基于铈的永磁金属间化合物潜力的基本限制。