Magnetic, thermal and transport properties of Tb₃Ru₄Al₁₂ with a distorted kagome lattice

The Tb₃Ru₄Al₁₂ compound (hexagonal crystal structure) having a distorted kagome net of the Tb atoms is studied on a single crystal by measurements of magnetization, specific heat and electrical resistivity. The system is an antiferromagnet with the Néel temperature T_N = 22 K. A substantial magnetic anisotropy is observed that persists at least up to 60 T. Tb₃Ru₄Al₁₂ displays field-induced magnetic phase transitions: one along [100] and [120] and two along the [001] axis. The transitions are accompanied by sharp peaks in magnetoresistance and subsequently lead to a large negative effect in it, −20% in the longitudinal and −40% in the transverse geometry. The peaks are explained by changes in conduction electron spectra at the transitions due to the interaction between the conduction electrons and localized magnetic moments. The large negative effect suggests field-induced magnetic phases with a reduced period as compared to zero field.