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Photoinduced Magnetic Effect in Magnetic Oxides

磁性氧化物中的光致磁效应

基本信息

批准号：
01550025
负责人：
HISATAKE Keizo
金额：
$ 1.41万
依托单位：
Kanagawa Dental College
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1991
项目状态：
已结题

项目摘要

Warming a sample of yttrium iron garnet after cooled to 77 K and illuminated with white light, the two types of mu_1(t) were simultaneously observed around 130 K ; an irreversible decrease so long as kept at low temperature and a reversible type or disaccommodation (DA). On warming the previously illuminated sample, the triple peaks of the imaginary part of permeability mu* were observed as a function of temperature. Furthermore, it was observed that each peak of mu* depends on the illuminating time. The lowest temperature peak is termed P_I, the intermediate temperature peak P_<II> and the highest temperature peak, P_<III>. From the Arrehnius plot of the frequency associated with each peak, the activation energies are obtained as 0.095-0.22eV for P_I, 0.5OeV for P_<II> and 0.81 eV for P_<III>, respectively. Next, a thermal variation of mu* has been studied as a function of light intensity l (time as a measure of intensity). The observation may be exphdned in terms of the one dimensional model of an oxygen vacancy which forms a ground state and three metastable excited levels In which an excited electron may spontaneously go to these levels via usually termed excited' level. Each of these metastable levels is assumed to have two magnetically equivalent potentials separated by barriers of activation energies U_<exc1>, U_<exc2> and U_<exc3> which are associated with P_I, P_<II> and P_<III>, respectively. These levels could be associated with "near", " intermediate " and or "far" site. In order to explain the dependence of these peaks we postulate a set of consecutive equations.

样品冷却至77K后，用白光照射加热，在130K附近同时观察到两种类型的mu1(T)，在低温下保持不可逆的下降和可逆型或失调(DA)。在加热先前照射的样品时，观察到作为温度的函数的磁导率虚部的三个峰。此外，还观察到各峰随光照时间的不同而变化。最低温度峰称为P_i，中间温度峰P_i；根据与各峰对应的频率的Arrehnius图，得到P_i的激活能为0.095-0.22 eV，P_l；II&gt；的激活能为0.5o eV，P_l；III&gt；的激活能为0.81 eV。接下来，研究了作为光强函数的Mu*的热变化L(时间作为强度的量度)。这种观察可以用氧空位的一维模型来解释，氧空位形成基态和三个亚稳态激发能级，在这些激发能级中，被激发的电子可以通过通常被称为激发‘能级自发地到达这些能级。假设这些亚稳态能级中的每一个都有两个磁等效势，分别由分别与P_i、P_l；II&gt；和P_i、P_t；II&gt；和P_i、P_t；这些水平可能与“近”、“中”和/或“远”部位有关。为了解释这些峰的相关性，我们假设了一组连续的方程。