High Magnetic Field X-ray Absorption and Magnetic Circular Dichroism Spectroscopy in the Mixed-Valent Compound YbAgCu_4
High Magnetic Field X-ray Absorption and Magnetic Circular Dichroism Spectroscopy in the Mixed-Valent Compound YbAgCu_4
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混价化合物YbAgCu_4的强磁场X射线吸收和磁圆二色光谱
DOI：
10.1143/jpsj.81.114702
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Akio Kotani
中科院分区：
文献类型：
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作者：
Toshiyuki Nakamura;Yasuhiro H. Matsuda;Jim-Long Her;Koichi Kindo;Shinji Michimura;Toshiya Inami;Masaichiro Mizumaki;Naomi Kawamura;Motohiro Suzuki;Bin Chen;Hiroto Ohta;Kazuyoshi Yoshimura;Akio Kotani
在高磁场和低温下，对混合价重费米子化合物 YbAgCu4 的 Yb L3 边缘的 X 射线吸收和磁圆二色性 (XMCD) 光谱进行了实验和理论研究。研究发现，吸收光谱取决于温度和磁场，表明价态随温度和磁场发生显着变化。由价态确定的磁场-温度（H-T）相界与由磁化强度确定的相界非常一致。清楚地发现该化合物的亚磁性是由于场诱导的价态跃迁所致。由于 Yb3+ 态，XMCD 光谱的明显正峰出现在吸收白线附近，而在与 Yb2+ 态相对应的 XMCD 光谱中没有观察到任何特征。另一方面，在较低能量下观察到小的负 XMCD 峰，并且发现负 XMCD 强度的磁场依赖性与白线附近的主 XMCD 信号的磁场依赖性有质的不同。通过理论计算，发现四极跃迁可以解释能量位置及其特有的磁场依赖性。
The X-ray absorption and magnetic circular dichroism (XMCD) spectra at theL3edge of Yb have been studied experimentally as well as theoretically in the mixed-valent heavy fermion compound YbAgCu4at high magnetic fields and low temperatures. It has been found that the absorption spectra depend on the temperature as well as the magnetic field, suggesting a significant change in valence with the temperature and magnetic field. The magnetic field–temperature (H–T) phase boundary determined by the valence state is in very good agreement with that determined by the magnetization. It is clearly found that the metamagnetism of this compound is due to the field-induced valence transition. A distinct positive peak of the XMCD spectra appears in the vicinity of the white line of the absorption due to the Yb3+state, while no feature is observed in the XMCD spectra corresponding to the Yb2+state. On the other hand, a small negative XMCD peak was observed at a lower energy and the magnetic field dependence of the negative XMCD intensity was found to be qualitatively different from that of the main XMCD signal near the white line. By theoretical calculation, the quadrupole transition is found to explain the energy position and its peculiar magnetic field dependence.