磁畴和畴壁的实验演示

利用透射光法进行磁畴和畴壁的实验演示，在磁性材料中的薄膜中，若无外加磁场时，可以观察到很多蜿蜒曲折的条状磁畴，当垂直薄膜面上加一个磁场（磁化场）时，这些条状磁畴就会产生变化，凡与外加磁场方向一致的磁畴体积扩大，与加外磁场方向相反的磁畴体积会缩小。     

直流偏场和面内场联合应用下第二类哑铃畴的自发收缩

实验研究了第二类哑铃畴在直流偏场和面内场联合应用下的自发收缩现象，发现第二类哑铃畴的自发收缩不仅与面内场的大小有关，而且不与第二类哑铃畴在面内场中所处方向有关。采用照相法形象地揭示出：当第二类哑铃畴与面内场垂直时最容易发生自发收缩；当第二类哑铃畴与面内场平行时最难发生自发收缩。     

三类硬磁畴的形成及静态特性

本文提出畴壁中含有大量VBL的石榴石磁泡材料的三类硬磁畴的分类标准,描述了它们的形成方法和静态特性,并示出典型照片。从形成条件可以合理地推论,畴壁中VBL数目的增加导致硬磁畴静态特性的质的变化。 关键词：     

面内场对三类硬磁畴的影响

采用直流偏场整形的方法,研究了面内场对石榴石磁泡薄膜中三类硬磁畴的影响.得到面内场作用下三类硬磁畴畴壁中垂直布洛赫线(VBL)是逐步解体的,而且三类硬磁畴具有相同的临界面内场范围［H¹_ip,H²_ip］,其中H¹_ip是硬磁畴中VBL开始丢失时的临界面内场,H²_ip是VBL完全丢失 关键词： 硬磁畴 整形 垂直布洛赫线     

脉冲偏场作用下石榴石磁泡薄膜中布洛赫线的形成

实验研究了石榴石磁泡薄膜中不同脉冲宽度下产生的硬磁畴的动态特性.结果表明：由零偏场下产生的枝状畴收缩而成的哑铃畴均逆时针转动,与产生枝状畴时所用的脉冲偏场的脉冲宽度无关.而固定直流偏场下由软畴段硬化而成的哑铃畴的转动状态,则与所用的硬化脉冲偏场的脉冲宽度有关.低脉冲宽度下硬化成的哑铃畴均逆时针转动,随硬化脉冲宽度的升高,出现混合转动向顺时针转动的过渡.由此揭示了直流偏场和脉冲偏场在石榴石磁泡薄膜中形成正、负垂直布洛赫线的作用. 关键词： 磁畴 磁泡 垂直布洛赫线     

直流偏场和面内场联合作用下第二类哑铃畴的自发收缩

实验研究了第二类哑铃畴在直流偏场和面内场联合作用下的自发收缩现象，发现第二类哑铃畴的自发收缩不仅与面内场的大小有关，而且还与第二类哑铃畴在面内场中所处方向有关.采用照相法形象地揭示出：当第二类哑铃畴与面内场垂直时最容易发生自发收缩；当第二类哑铃畴与面内场平行时最难发生自发收缩.实验还证明了第二类哑铃畴在自发收缩过程中存在垂直布洛赫线的丢失现象.     

高温超导圆柱在不同脉冲宽度磁场作用下的温度和磁场分析

多脉冲分段冷却磁化技术是获得强俘获磁场的一种有效方法,近年来受到广泛关注,脉冲磁场的幅值和宽度是影响该方法的两个重要因素。文中通过求解基本的超导电磁场和温度场耦合方程,研究了两种不同脉冲宽度情形下脉冲磁化过程中超导体磁场和温度场的变化。结果表明,宽脉冲作用下超导体在磁化过程中温度较低,分布均匀,而且有更多磁通进入超导体。     

色交叉关联噪声作用下集合种群的稳定性和平均灭绝时间

在Levins模型的基础上研究了色交叉关联噪声对集合种群稳定性的影响, 应用Fokker-Plank方程得到了系统的稳态概率密度函数, 运用最快下降法得到了平均灭绝时间的解析式. 结果表明: 两噪声色关联时, 加性噪声强度和乘性噪声强度均弱化集合种群的稳定性; 噪声关联强度强化集合种群的稳定性. 两噪声之间负关联时, 平均灭绝时间是加性噪声强度和乘性噪声强度的减函数, 是噪声关联时间的增函数; 两噪声之间正关联时, 平均灭绝时间是加性噪声强度和噪声关联时间乘性噪声强度的减函数, 是乘性噪声强度的非单调函数. 关键词： 集合种群 色交叉关联噪声 稳定性 平均灭绝时间     

随机脉冲微分方程的p阶矩稳定性和参激白噪声作用下Lorenz系统的脉冲同步

考察了随机脉冲微分系统的p阶矩稳定性问题,在更符合脉冲系统一般假设的情况下,建立了条件更弱的随机脉冲微分系统p阶矩稳定性判定定理.并应用该判定定理,考察了参激白噪声作用下Lorenz系统的脉冲同步问题,证明了同步误差系统的p阶矩稳定性,从而说明在p阶矩的意义下,两个系统是可以用脉冲方法实现同步的.数值模拟验证了随机Lorenz系统脉冲同步的可行性.     

随机脉冲微分方程的p阶矩稳定性和参激白噪声作用下Lorenz系统的脉冲同步

考察了随机脉冲微分系统的p阶矩稳定性问题,在更符合脉冲系统一般假设的情况下,建立了条件更弱的随机脉冲微分系统p阶矩稳定性判定定理.并应用该判定定理,考察了参激白噪声作用下Lorenz系统的脉冲同步问题,证明了同步误差系统的p阶矩稳定性,从而说明在p阶矩的意义下,两个系统是可以用脉冲方法实现同步的.数值模拟验证了随机Lorenz系统脉冲同步的可行性. 关键词： 随机脉冲微分方程 p阶矩稳定性')" href="#">p阶矩稳定性 脉冲 同步     

STABILITY OF SECOND KIND OF DUMBBELL DOMAINS SUBJECTED TO AN IN-PLANE FIELD AT DIFFERENT BIAS FIELDS

The softening process of the second kind of dumbbell domalns(liDs) in garnet bubble films subjected to an in-plane field H_ip at different static bias field H_b was studied experimentally. It was found that when H_b is larger, the remaining percentage of IID, R_IID, drops sharply at a certain H_ip, and with the increase of H_b the drop occurs at lower H_ip and becomes more intensive. We have confirmed that this is related to the "spontaneous-shrink" 0f IIDs, which plays an important role for the breakdown oF vertical Bloeh line chains of lids subjected to joint fields H_ip and H_b .     

ANNIHILATION OF VERTICAL-BLOCH-LINE CHAINS IN THE WALLS OF THE SECOND KIND OF DUMBBELL DOMAINS SUBJECTED TO JOINT STATIC BIAS FIELD AND IN-PLANE FIELD

Experiments were statistically carried out on the behavior of vertical-Bloch-line(VBL) chains in the walls of the second kind of dumbbell domains (IIDs) is garnet bubble films subjected to joint action of static bias field H_b and in-plane field H_ip. The curves of the four critical in-plane fields, (H_ip)_IID-ID (H_ip)_IID-OHB (H_ip)_IID-SB and H'_ip vs H_b were measured and explained. In particular, in terms of two series of IID photos, a new experimental manifestation of the unknown "number effect" of VBL chains was found.     

INFLUENCE OF IN-PLANE FIELD ON THE STABILITY OF VERTICAL BLOCH LINE CHAINS IN HARD DOMAINS OF GARNET BUBBLE FILMS

The stability of vertical Bloch line (VBL) chains was statistically studied for all three types of bard domains in garnet bubble films subjected to an in-plane field H_ip. With a set of integrate data taken from seven bubble samples and with two typical figures of a sample, four main features of the behavior of VBL chains subjected to H_ip were summarized.     

ANNIHILATION OF VERTICAL-BLOCH-LINE CHAINS IN THE WALLS OF ORDINARY HARD BUBBLES SUBJECTED TO JOINT STATIC BIAS FIELD AND IN-PLANE FIELD

For the ordinary hard bubbles(OHBs) of garnet bubble films, the annihilation of the vertical-Bloch line (VBL) chains in their walls subjected to joint static bias field H_b and in plane field H_ip was experimentally studied. The curves of two critical in-plane fields, H⁽¹⁾_ip and H′_ip, vs H_b were measured. By means of the so-called "head-cut" and "tail-cut" experiments designed in this work, it was verified that for the OHBs subjected to H_ip, their VBL chains with different lengths lose VBLs and become shorter simultaneously. It was also verified that the critical in-plane fields H⁽¹⁾_ipand H′_ip correspond to the break down of the shortest and longest VBL chains of OHBs, respectively.     

RADIAL CONTRACTION OF THE FIRST KIND OF DUMBBELL DOMAINS SUBJECTED TO A STATIC BIAS FIELD

On the basis of the "exercise" experiment and the phenomenon of "self-shrink", the behavior of "less-stable" IDs (first kind of dumbbell domains) in radial contraction under an "exercise" bias field, (H_b)_e, was statistically investigated in detail. It was found that the histograms of their stripe-to-bubble transition field, H_sb after exercise, become narrower and shift towards the side of lower H_sb with the increase of (H_b)_e. It illustrates how the less-stable IDs lose part of their vertical Bloch lines under different (H_b)_e. In addition, it was also found that the curve of the upper boundary of these histograms, (H_sb)_max vs. (H_b)_e, consists of two segments of straight lines. This discontinuity was proved to be due to self shrink, and the crosspoint of these two lines is just the lower limit of the self-shrink region. Furthermore, a series of photographs were taken to show the effect of radial contraction on less-stable IDs intuitively.     

立方磁晶各向异性对面内磁场中条畴和磁泡稳定性的影响

在八个(111)面磁泡膜上,观察了施加面内(in-plane)磁场后在不同晶轴方向上条状畴的消失过程,测量了条畴消失场H_s^*和磁畴消失场H_k^*与面内磁场的方向的关系。本文计及立方磁晶各向异性,完善了面内磁场中条畴的稳定性理论。用该理论定性地解释了实验结果的主要特点。导出了H_s^*与立方各向异性及面内场方向的两种近似的理论关系,它们分别适用于面内场方向靠近和不十分靠近〈110〉晶轴的情形。它们和实验结果是大致符合的。在〈110〉晶轴上,理论关系具有下列简单的形式:H_k^*<110>=H_s^*<110>=H_k{1+(k₁/2K_u)-[al/h(4πM_s/H_k)²]^2/3},此式与实验结果符合得相当好。 关键词：     

脉冲偏场作用下硬磁泡的形成

对低频脉冲偏场产生磁泡的过程中硬磁泡的形成条件进行了实验研究。发现硬磁泡的百分比p随着脉冲偏场强度的增加而迅速减小,同时发现存在一临界脉冲偏场强度H_po,当H_p≥H_po时,所产生的磁泡都是软磁泡。 关键词：     

斜向静磁场中的薄膜磁光效应和静磁波传播特性

理论计算表明，与垂直静磁场情形相比，斜向静磁场可以明显增强磁性薄膜波导中的法拉第效应，同时会引起静磁波共振频率和带宽等许多静磁波特性的变化.合理利用这些变化特性，可望大幅度提高导波光的衍射效率，改善磁光波导器件的特性. 关键词：