Specific features of temperature dependence of heat capacity and low-frequency ohmic loss of LuFe_4Al_8

摘要

The temperature dependence of the impedance in the compound LuFe_4Al_8 is studied at the frequencies 0-10~7 Hz and temperatures 4.2-300 K. The temperature dependences of heat capacity are measured at 1.5-120 K. The antiferromagnetic ordering is shown to occur at T_N=100.5 K. It is found that a magnetostructural phase transition takes place at T_1 several Kelvins below T_N. In this case the antiferromagnetically coupled Fe layers are formed, which are separated by nonmagnetic Lu interlayers. In this phase the LuFe_4Al_8 structure is a specific Fe-Lu-Fe superlattice. In weak magnetic fields it has negative magnetoresistance due to spin-dependent scattering of charge carriers. It is found that at T_c<25 K the compound becomes superconducting.