【摘要】 采用固相反应法制备巨磁电阻材料La0.67Ca0.33MnO3,测试其电子自旋共振,并采用自旋波理论解释自旋共振线宽的变化.通过对自旋波能量的计算机自洽计算,得到了自旋相互作用的重正化因子{1-e(T)/S},重正化因子随体系温度升高而降低表明,温度上升导致自旋波频率发生软化现象,使得体系结构不稳定,由此可知实验未探测到相变区自旋波能量的原因.理论计算表明,自旋共振线宽随温度升高而减小是由于自旋波耦合模的数目减少所致.更多还原

【Abstract】 The sample of La0.67Ca0.33MnO3 was prepared by a conventional solid state reaction method.The electron spin resonance behavior of La0.67Ca0.33MnO3 was studied experimentally.The variations of electron spin resonance linewidth were investigated by spin wave theory.A self-consistent calculation of spin wave energy was carried out in the regime of renormalization group theory,and a renormalization factor {1-e(T)/S} was obtained to correct the temperature dependent spin wave energy.It shows that the spin wave frequency is softened with the increase of the temperature,leading to an unstable state.Therefore,the reason of the disappearance of spin wave energy at the critical temperature is well understood theoretically.We theoretically validate the conclusion that the decrease of the electron spin resonance line-width with temperature increase is the result of the decrease of the number of the spin wave coupling modes.更多还原