Due to their outstanding dielectric and magnetic properties, hexaferrites are attracting ever-increasing attention for developing electronic components of next-generation communication systems. The complex crystal structure of hexaferrites and the critical dependences of their electric and magnetic properties on external factors, such as magnetic/electric fields, pressure, and doping, open ample opportunities for targeted tuning of these properties when designing specific devices. Here we explored the electromagnetic properties of lead-substituted barium hexaferrite, Ba_1−xPb_xFe₁₂O₁₉, a compound featuring an extremely rich set of physical phenomena that are inherent in the dielectric and magnetic subsystems and can have a significant effect on its electromagnetic response at terahertz frequencies. We performed the first detailed measurements of the temperature-dependent (5–300 K) dielectric response of single-crystalline Ba_1−xPb_xFe₁₂O₁₉ in an extremely broad spectral range of 1 Hz–240 THz. We fully analyzed numerous phenomena with a corresponding wide distribution of specific energies that can affect the terahertz properties of the material. The most important fundamental finding is the observation of a ferroelectric-like terahertz excitation with an unusual temperature behavior of its frequency and strength. We suggest microscopic models that explain the origin of the excitation and its nonstandard temperature evolution. Several narrower terahertz excitations are associated with electronic transitions between the fine-structure components of the Fe²⁺ ground state. The discovered radio-frequency relaxations are attributed to the response of magnetic domains. Gigahertz resonances are presumably of magnetoelectric origin. The obtained data on diverse electromagnetic properties of Ba_1−xPb_xFe₁₂O₁₉ compounds provide information that makes the entire class of hexaferrites attractive for manufacturing electronic devices for the terahertz range.

由于其出色的介电和磁性能，六铁氧体在开发下一代通信系统的电子元件方面受到越来越多的关注。六铁氧体的复杂晶体结构及其电磁特性对外部因素（如磁场/电场、压力和掺杂）的关键依赖性，为设计特定器件时有针对性地调整这些特性提供了充足的机会。在这里，我们探索了铅取代的六铁酸钡 Ba _{1− x} Pb _x Fe ₁₂ O ₁₉的电磁特性，一种化合物，具有一组极其丰富的物理现象，这些物理现象是介电和磁性子系统固有的，可以对其在太赫兹频率下的电磁响应产生显着影响。我们对单晶 Ba _{1− x} Pb _x Fe ₁₂ O ₁₉的温度相关 (5–300 K) 介电响应进行了首次详细测量在 1 Hz–240 THz 的极宽光谱范围内。我们充分分析了大量具有相应广泛分布的特定能量现象，这些现象会影响材料的太赫兹特性。最重要的基本发现是观察到类似铁电的太赫兹激发，其频率和强度具有不寻常的温度行为。我们建议解释激发起源及其非标准温度演变的微观模型。几个较窄的太赫兹激发与 Fe ²⁺的精细结构组分之间的电子跃迁有关基态。发现的射频弛豫归因于磁畴的响应。千兆赫兹共振可能是磁电起源的。获得的关于 Ba _{1− x} Pb _x Fe ₁₂ O ₁₉化合物的各种电磁特性的数据提供的信息使整个六铁氧体类对制造太赫兹范围的电子设备具有吸引力。