石榴石高功率临界场h_c(H)蝶形曲线形状和拐点磁场与晶粒尺寸关系研究  

Study on the Grain Size Dependence of Butterfly Curves of Spinwave Instable Thresholds for Garnets

作　　者：韩志全[1] 

机构地区：[1]西南应用磁学研究所,四川绵阳621000

出　　处：《磁性材料及器件》2006年第6期20-23,41,共5页Journal of Magnetic Materials and Devices

摘　　要：观测了三组晶粒尺寸不同的钇钆钆石榴石YGdIGs和铋钙钒石榴石BiCaVIGs样品在平行激励下的高功率临界场hc与外加直流磁场H的关系,发现了阶状蝶形曲线。金相分析表明这可能与晶粒均匀性有关。实验表明隔离器的功率承受能力与材料蝶形曲线拐点磁场以上的走势密切相关。基于渡越时间模型讨论了观测到的蝶形曲线拐点磁场H′min与晶粒尺寸的关系。分析了Patton和Borghese在关于自旋波不稳定模最低波数kmin及相应的H′min上的不同观点和所分别适用的粗、细晶粒场合。用存在有表面感生各向异性场Hs的晶粒表层模型解释了渡越时间理论。The influence of grain size on the butterfly curve of the nonlinear threshold hc vs applied field H for parallel pumping was investigated on the garnet samples, YGdlG and BiCaVIG A stepped shape of butterfly curve was observed in a sample with inhomogeneous grain size. R was found that the power level of the isolator using the materials strongly depends on the behavior of the butterfly curve at H〉 Hmin＇ （the field corresponding to hc（min））. Based on the theory of transit-time limited magnon lifetime, the values of field Hmin＇ are compared with their theoretical value Hmin, for six samples with various rough or fine grains. The separations between the experimental value Hmin＇ and the theoretical value Hmin are discussed. These curves evidence that the Patton＇s opinion of constant kmin and the Borghese＇s opinion of shifting Hmin＇ position with grain size suits for different available ranges of grain size, i.e. respectively for the samples with rough grain and the samples with fine grain. The theory of transit-time is explained using the model of grain-surface-layer having surface-induced anisotropic field.

关 键 词：微波铁氧体 高功率临界场 自旋波不稳定模 YIG 

分 类 号：TM277.3[一般工业技术—材料科学与工程] O482.5[电气工程—电工理论与新技术]