De Haas-van Alphen Effect of Heavy Electron Systems with non-Fermi Liquid behavior

利用De Haas-van Alphen(DHvA)效应对重电子体系CeNi2Ge2的费米面进行了研究。研究了极低剩余电阻率的晶体生长方法。此外，我们还测量了参考物质LaNi2Ge2的dHvA效应。结果：在以下条件下可以得到质量较好的单晶：1)用电输运方法对原料Ce进行预提纯。2)用晶种沿[001]方向生长。对于最好的样品，仅在距单晶棒颈点20 mm处获得的剩余电阻率为1.5μΩcm，X射线摇摆曲线的半宽为0.2度。没有观察到CeNi2Ge2的dHvA效应，这可能是由于CeNi2Ge2的重电子质量所致。我们将在未来尝试在低于3He的温度下进行观测。另一方面，我们成功地测量了LaNi2Ge2的dHvA效应，并与计算的费米面进行了比较，得到了与能带计算很好的一致性。我们还用非弹性中子散射和电阻率研究了磁关联和超导电性。发现在低于30K的温度下存在弱的反铁磁关联，在低于300mK的常压和2~5 Gpa的压力下也存在超导电性。

The Fermi surface study of CeNi2Ge2, which is a heavy electron system showing non-Fermi liquid behavior, by means of de Haas-van Alphen (dHvA) effect was intended. The method of crystal growth with very low residual resistivity was studied. Further, we perfoemed to measure the dHvA effect of the reference material LaNi2Ge2.RESULTS : A good quality single crystals could be obtained in the following conditions : 1) Pre-purification of the raw material of Ce using electro-transport method. 2) Growth along the [001] direction using the seed. For the best specimen, which was only obtained at the position up to 20 mm from the neck point of the single crystal rod, the residual resistivity was 1.5 μΩ cm and the half width of the X-ray rocking curve, (004) reflection, was 0.2 degrees. The dHvA effect of CeNi2Ge2 could not be observed, probably due to the heavy electron masses. We will try to observe at a temperatures lower than 3He temperature in a future. On the other hand, we suceeded to measure the dHvA effect of LaNi2Ge2, and compared to the Fermi surfaces calculated, obtaining very good agreement between the experiment and the band calculaion.We also studied the magnetic correlation and the superconductivity, using the inelastic nutron scattering and the electrical resistivity. It was found the weak antiferromagnetic correlation exists at temperatures lower than 30 K, and the superconductivity also was found at ambient pressure and at pressures from 2 GPa to 5 GPa at temperatures lower than 300 mK.