Valence Crossover of Ce Ions in CeCu2Si2 under High Pressure - Pressure Dependence of the Unit Cell Volume and the NQR Frequency

被引：16

作者：

Kobayashi, Tatsuo C. ^{[1
]}

Fujiwara, Kenji ^{[2
]}

Takeda, Keiki ^{[3
]}

Harima, Hisatomo ^{[4
]}

Ikeda, Yoichi ^{[1
]}

Adachi, Takafumi ^{[5
]}

Ohishi, Yasuo ^{[5
]}

Geibel, Christoph ^{[6
]}

Steglich, Frank ^{[6
]}

机构：

[1] Okayama Univ, Dept Phys, Okayama 7008530, Japan

[2] Shimane Univ, Dept Mat Sci, Matsue, Shimane 6908504, Japan

[3] Muroran Inst Technol, Dept Elect & Elect Engn, Muroran, Hokkaido 0508585, Japan

[4] Kobe Univ, Dept Phys, Kobe, Hyogo 6578501, Japan

[5] JASRI, SPring 8, Sayo, Hyogo 6795198, Japan

[6] Max Planck Inst Chem Phys Solids, D-01187 Dresden, Germany

来源：

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN | 2013年 / 82卷 / 11期

基金：

日本学术振兴会;

关键词：

heavy fermion; high pressure; X-ray diffraction; NQR; superconductivity; SUPERCONDUCTING TRANSITION-TEMPERATURE; CECU2GE2; ENHANCEMENT; MAGNETISM; STATE;

D O I：

10.7566/JPSJ.82.114701

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

The pressure dependence of the valence of Ce ions in CeCu2Si2 has been investigated by means of X-ray powder diffraction (XRPD) and nuclear quadrupole resonance (NQR) measurements. The high-pressure XRPD measurements were carried out at 12K for CeCu2Si2 and CeCu2Ge2. Precise measurements under smoothly-applied pressure were achieved through the selection of the gasket material of a diamond anvil cell. The jump of the unit cell volume, which was reported previously in CeCu2Ge2, was not observed within the experimental accuracy, indicating the absence of a first-order valance transition. The pressure dependence of Cu-63-NQR frequency nu(Q) measured in CeCu2Si2 was compared with that calculated from the measured lattice parameters. The nu(Q)'s were calculated for the two cases of LaCu2Si2 and CeCu2Si2, corresponding to localized and itinerant cases for 4f electrons, respectively. The measured and calculated slopes d nu(Q)/dP show good agreement. A small but significant deviation from the pressure-linear dependence in nu(Q) was observed in the narrow pressure range of 3.9-4.5 GPa, indicating a valence crossover adjacent to the critical end point.

引用

页数：6

共 29 条

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