Magnetism and Electronic States of X 2 Co 12 P 7 ( X = Ti, Zr and Hf)
Magnetism and Electronic States of X 2 Co 12 P 7 ( X = Ti, Zr and Hf)
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DOI：
10.2497/jjspm.65.274
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发表时间：
2018-05
期刊：
影响因子：
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通讯作者：
Y. Kato;H. Ohta;H. Katori
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文献类型：
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作者：
Y. Kato;H. Ohta;H. Katori
为了阐明X_2Co_（12）P_7（X = Ti，Zr和Hf）的磁性和电子态，即四价态和三价态，我们测量了X_2Co_（12）P_7多晶样品的磁化强度，并将它们的磁性行为与居里温度TC约为150 K的巡游铁磁体Ln_（2Co）_（12）P_7（Ln =镧系元素）的磁性行为进行了比较。作为磁化强度测量的结果，我们发现这些化合物显示巡回铁磁性与TC = 67，149和133 K的X = Ti，Zr和Hf，分别。这种行为与Ln2Co12P7的情况相反，在Ln2Co12P7中TC几乎不依赖于Ln。X = Ti的情况下的TC比Ln2Co12P7低，表明该化合物中Ti的价态为+4而不是+3，并且由于来自Ti的电子掺杂，来自Co的铁磁性减弱。另一方面，在X = Zr和Hf化合物的情况下，两个TC具有与Ln 2Co 12 P7的TC相似的值，表明X几乎处于三价状态。从磁化强度测量的结果，很明显，有没有在这些化合物的局域磁矩。因此，三价Zr或Hf中的d电子在X2Co12P7中表现出巡游性质。
To elucidate magnetism and electronic states of X2Co12P7 with X = Ti, Zr and Hf, which are expected to be in a tetravalent state or a trivalent state with one d-electron, we measured magnetizations of polycrystalline samples of X2Co12P7 and compared their magnetic behaviors with that of itinerant ferromagnets Ln2Co12P7 (Ln = lanthanoids), the Curie temperature TC of which is approximately 150 K. As results of magnetization measurements, we found these compounds to show itinerant ferromagnetism with TC = 67, 149 and 133 K for X = Ti, Zr and Hf, respectively. This behavior is in contrast to the case of Ln2Co12P7 in which TC is almost independent of Ln. The lower TC for the case of X = Ti compared with Ln2Co12P7 suggests that the valence of Ti in this compound is +4 rather than +3 and ferromagnetism derived from Co is weakened due to the electron doping from Ti. On the other hand, in the case of X = Zr and Hf compounds, both TC have similar values to that for Ln2Co12P7, indicating that X are almost in the trivalent state. From the result of magnetization measurements, it is clear that there is no localized magnetic moment in these compounds. Therefore, d-electrons in trivalent Zr or Hf show itinerant nature in X2Co12P7.