AI 中文总结
研究重费米子材料磁致变磁性中磁各向异性的微观起源及相关谜题。通过发展解析c-f理论，以混合磁化率统一各向异性响应，用UTe₂数据检验，建立了相干驱动框架，适用于多种重费米子化合物。
AI 中文摘要
许多重费米子材料表现出磁场诱导的磁致变磁性：沿硬磁轴施加磁场时，磁化强度先逐渐上升，达到临界场时会突然跃升。尽管经过数十年的唯象学建模，这种行为背后明显磁各向异性的微观起源仍未解决。相关的长期谜题——硬轴磁化率随温度的异常最大值也是如此。在5f化合物中，相关电子的双重局域-巡游特性使这两个问题变得更加复杂。在此，我们发展了重费米子变磁体中磁各向异性的解析c-f理论，将混合磁化率χcf(T,h,p)确定为一个单一的热力学可观测量，它统一了温度、场和压力下的各向异性响应。我们用重费米子超导体UTe₂的主要数据和文献数据检验了该理论，发现其磁各向异性在温度、场和压力演化方面有出色的定量一致性——包括反常硬轴磁化率最大值的近藤相干起源，我们证明它与变磁转变本身直接相关。我们的结果为各向异性磁致变磁性建立了一个通用的、微观的、相干驱动的框架，适用于表现出这种现象的广泛重费米子化合物类别。
英文摘要
A number of heavy-fermion materials exhibit magnetic field-induced metamagnetism: on applying a field along the magnetic hard axis, the magnetization first rises gradually, then jumps abruptly once a critical field is reached. Despite decades of phenomenological modeling, the microscopic origin of the pronounced magnetic anisotropy underlying this behavior has remained unresolved. The same is true of a related, long-standing puzzle: an anomalous maximum in the hard-axis susceptibility versus temperature. Both are complicated in $5f$ compounds by the dual localized-itinerant character of the relevant electrons. Here we develop an analytic $c$--$f$ theory of magnetic anisotropy in heavy-fermion metamagnets, identifying the mixed susceptibility $χ_{\rm cf}(T,h,p)$ as a single thermodynamic observable that unifies the anisotropic response across temperature, field, and pressure. We test this theory against primary and literature data for the heavy-fermion superconductor UTe$_2$, finding excellent quantitative agreement in the temperature, field, and pressure evolution of its magnetic anisotropy -- including a Kondo-coherence origin for the anomalous hard-axis susceptibility maximum, which we show is directly connected to the metamagnetic transition itself. Our results establish a general, microscopic, coherence-driven framework for anisotropic metamagnetism, applicable across the broad class of heavy-fermion compounds that display this phenomenology.
