【摘要】 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 0 0 2 3) ,线宽随温度呈线性变化等 ;而在Tmin以下 ,共振谱明显畸变 ,如不对称的谱型、不寻常的与温度有关的 g值以及随温度反常变化的线宽等 .这些结果意味着 ,完全的顺磁性只出现在T >Tmin温区 ,而在TC<T <Tmin温区 ,因磁不均匀性而导致顺磁行为的反常 .文中基于交换变窄的自旋 自旋相互作用和自旋晶格弛豫机理 ,对Tmin以上温区线宽的起因也进行了讨论更多还原

【Abstract】 The electron spin resonance behavior of two typical systems with Mn\+\{3+\}/Mn\+\{4+\}=2∶1 and 1∶1 within the temperature range \%T\%>T C is studied experimentally. The results show that there exists a temperatureT min (>T C)dividing the magnetic behavior above T C into two distinguishable regime. While \%T\%>T min , 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 increases linearly with increasing temperature. Some distortions are observed when the temperature is lower than T min . The line shape becomes unsymmetrical. The g factor become dependent on the temperature and the linewidth increases anomalously with decreasing temperature. These results point out that the complete paramagnetism exits only in the temperature range \%T\%>T min . When T C<\%T\%<T min ,the anomalous paramagnetic behavior may be caused by the magnetic inhomogeneity. The mechanism of resonance linewidth broadening is discussed based on an analysis of the linewidth above T min , suggesting that the exchange narrowing spin\|spin interaction and the spin\|lattice interaction are two possible reasons of linewidth changes in the high temperature regime.更多还原