Magnetic order, phase transitions and electrical resistivity of Ho7Rh3 single crystals

Abstract

Field-induced magnetic phase transitions have been studied on Ho7Rh3 single crystals with the hexagonal Th7Fe3 structure by measuring the magnetization and electrical resistivity as a function of temperature and applied magnetic field. The Ho7Rh3 compound having an antiferromagnetic (AF) order below TN = 32.0 K enters other magnetic states with decreasing temperature below Tt2 = 23.5 K and Tt1 = 9.0 K. Below Tt2, Ho7Rh3 possesses a small ferromagnetic component in the c-plane. Meanwhile, two successive metamagnetic transitions were observed in magnetic fields up to 100 kOe applied along the b-axis at T < Tt2. The metamagnetic phase transitions from AF to the forced ferromagnetic state in magnetic fields applied in the basal plane are observed to be accompanied by a large magnetoresistance (|Δρ/ρ| ∼ 42%). When the magnetic field is applied along the c-axis, the superzone gap effect on the electrical resistivity below TN does not disappear even under 100 kOe. In the paramagnetic state, the additional magnetic contribution to the electrical resistivity is found to persist apparently because of the conduction electron scattering by the short ranged antiferromagnetic clusters and spin fluctuations in the Rh 4d electron subsystem, which leads to the negative temperature coefficient of the electrical resistivity.