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中国物理学会期刊

钙钛矿Mn基氧化物的电子顺磁共振行为的实验研究

CSTR: 32037.14.aps.49.1846

ELECTRONIC SPIN RESONANCE STUDY OF PEROVSKITE-TYPE MANGANITES

CSTR: 32037.14.aps.49.1846
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  • 借助电子顺磁共振技术,对Mn3+/Mn4+=2∶1和1∶1的两个典型体系 在居里温度TC以上温区的顺磁行为进行了实验研究.实验表明,存在一特征温度 Tmin,通过该温度将TC以上的磁行为分成两个明显可区分的温区: 在Tmin以上,共振谱由一对称的单线构成,Lande 因子g值与温度无关且接近 自由电子的值(~20023),线宽随温度呈线性变化等;而在Tmin 

    The electron spin resonance behavior of two typical systems with Mn3+ /Mn4+=2∶1 and 1∶1 within the temperature range T>TC is s tudied experimentally. The results show that there exists a temperature Tmi n(>TC)dividing the magnetic behavior above TC into t wo distinguishable regime. While T>Tmin, The ESR spectrum consists of one symmetrical resonance line. The Lande factor is independent of temperature and close to the value of free electron (~20023), and the linewidth increase s linearly with increasing temperature. Some distortions are observed when the t emperature is lower than Tmin. The line shape becomes unsymmetrical. The g factor become dependent on the temperature and the linewidth increases ano malously with decreasing temperature. These results point out that the complete paramagnetism exits only in the temperature range T>Tmin. When T Cmin,the anomalous paramagnetic behavior may be caused by t he magnetic inhomogeneity. The mechanism of resonance linewidth broadening is di scussed based on an analysis of the linewidth above Tmin, suggesting that the exchange narrowing spin-spin interaction and the spin-lattice interacti on are two possible reasons of linewidth changes in the high temperature regime.

     

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