Quantum critical behaviors induced by a magnetic frustration in 4f hole systems under pressures

2015 Fiscal Year Final Research Report

• Project/Area Number: 25400375
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Hiroshima University
• Principal Investigator: Umeo Kazunori 広島大学, 自然科学研究支援開発センター, 准教授 (10223596)
• Co-Investigator(Renkei-kenkyūsha): TAKABATAKE Toshiro 広島大学, 大学院先端物質科学研究科, 教授 (40171540)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 高圧力 / 量子臨界現象 / ４fホール系 / フラストレーション

Outline of Final Research Achievements

We developed a low-temperature AC calorimeter for measuring the absolute value of specific heat under pressures up to 10 GPa.
In YbAgGe, Yb atoms form a quasi-kagome lattice in the hexagonal c-plane. With increasing x of YbAg1-xAuxGe, We found that the magnetic ordering temperature at 0.8 K increases up to 1.3 K for x = 0.11, while the Kondo temperature rises. These observations suggest that the magnetic frustration in the Yb sublattice is released by the atomic disorder in the nonmagnetic Ag-Ge sublattice. We have investigated the uniaxial and hydrostatic pressure effects on the antiferromagnetic order at TN=4.2 K of YbCuGe with a triangular lattice of Yb ions. For P//a up to 0.17 GPa, where the Yb triangular lattice is distorted, the TN increases up to 4.5 K. These contrasting responses indicate that the distortion under P//a releases the magnetic frustration and stabilizes the antiferromagnetic order in YbCuGe.

Free Research Field

低温高圧物性