ANISOTROPIC THERMAL-EXPANSION OF HEAVY FERMION MATERIAL CECU6

The thermal expansion of single-crystalline CeCu6 and LaCu6 has been measured by using the strain gauge method in the temperature range from 6 K to 300 K. A large anisotropy was found in the temperature dependence of thermal expansion (Δl/l)i(i denotes the crystal axis, i=a, b and c). The contribution of the 4f electron to thermal expansion is very large for the b-axis and extremely small for the a-axis. The thermal expansion coefficient α was also estimated from these data. An anomalous enhancement in the αl/T vs T2 plot (α1=1/3 (αa+αb+αc)) was found at low temperature below about 20 K, which is considered to correspond to the large enhancement of the C/T value at low temperatures where C is the specific heat. These results are discussed in connection with other heavy fermion materials. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.