Paramagnetic hyperfine splitting in the Eu Mössbauer spectra of CaF(2):Eu.
Paramagnetic hyperfine splitting in the Eu Mössbauer spectra of CaF(2):Eu.
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CaF(2):Eu 的 Eu 穆斯堡尔谱中的顺磁超精细分裂。
DOI：
10.1103/physrevb.77.224442
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Schweizer,S
中科院分区：
文献类型：
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作者：
Selling,J;Bielemeier,B;Wortmann,G;Johnson,JA;Alp,EE;Chen,T;Brown,DE;Johnson,CE;Schweizer,S
在零磁场下，高浓度（0.1mol%）离子的穆斯堡尔谱显示出几乎与温度无关的不对称分裂模式，这是由于在具有慢电子自旋弛豫的立方晶场中的顺磁超精细相互作用引起的;在0.2T的小外磁场下，观察到几乎对称的模式。使用自旋哈密顿量和以前的电子顺磁共振数据很好地描述了有和没有外场的光谱。浓度更高的样品（2mol%）由于Eu-Eu自旋弛豫速率增加而表现出强烈加宽的对称共振线;在0.2T的外磁场中，穆斯堡尔谱由于弛豫速率降低而表现出进一步加宽和额外的磁性结构。当施加一个大的场为6 T，这样的thatis远大于晶体场分裂，一个完全解决的超精细图案，观察到在2.5 K，与有效字段在Eu核;在更高的温度下，叠加图案源自激发电子态的光谱中观察到。目前的结果对高度稀释的样品提供了一个简单的解释，以前的观察，一个看似很大的依赖性的同分异构体位移铕浓度。
Mössbauer spectra in zero magnetic field of highly dilute (0.1 mol%)ions inshowed an almost temperature-independent asymmetrically split pattern, arising from the paramagnetic hyperfine interactionin a cubic crystal field with slow electron spin relaxation; in a small external magnetic fieldof 0.2 T such thatan almost symmetrical pattern was observed. Both the spectra with and without external field are well described using the spin Hamiltonian and previous electron paramagnetic resonance data. A more concentrated (2 mol%) sample exhibited a strongly broadened symmetrical resonance line due to an increased Eu-Eu spin relaxation rate; in an external magnetic field of 0.2 T the Mössbauer spectra exhibited further broadening and additional magnetic structures due to the reduced relaxation rate. When a large field of 6 T was applied such thatis much larger than the crystal field splitting, a fully resolved hyperfine pattern was observed at 2.5 K, with an effective field at the Eu nuclei of; at higher temperatures superimposed patterns originating from excited electronic states were observed in the spectra. The present results on the highly dilutesample deliver a straightforward explanation for previous observations of a seemingly large dependence of theisomer shift on europium concentration.