Structural and magnetic phase transitions of kagome-like compounds REBaCo_4O_7 (RE = Dy, Ho, Er, Tm, Yb, Lu)

摘要

In a temperature range 5-300 K the specific heat C(T) on a new mixed valence cobalt oxides REBaCo_4O_7 (RE = Dy, Ho, Er, Tm, Yb, Lu) was investigated. The first-order structural phase transitions from hexagonal P6_3mc to orthorhombic Cmc_21 phase was indicated by a peak-like anomaly in C(T) curves at T_S~160,178,224, and 280 K for RE = Lu, Yb, Tm, and Er correspondingly. The magnetic phase transitions was indicated as the changes of slope on the C(T) curves were found at corresponding temperatures: T_N~50, 74, 98, and 98 K for RE = Lu, Yb, Tm, and Er, correspondingly.