Abstract
Magnetism in EuNiIn4 is studied using specific heat, magnetic susceptibility, magnetization, 151Eu Mössbauer spectroscopy, and neutron diffraction experiments. The specific heat exhibited two magnetic transitions at TN1 = 15.2 K and TN2 = 14.3 K at zero magnetic field. An antiferromagnetic ground state of EuNiIn4 was observed to have a uniaxial magnetic anisotropy along the b axis using magnetic susceptibility and 151Eu Mössbauer spectroscopy. Further, single crystal neutron diffraction experiments illustrated that this antiferromagnetic structure in the ground state is characterized by the commensurate propagation vector q=(1/2,1/2,1/2), which reveals no distinct anomaly at TN2. The magnetization curve along the b axis at 2 K was observed to exhibit four successive magnetic field-induced transitions up to 50 kOe, following which it increased linearly, resulting in saturated magnetization of 7 μB/f.u. above 195.2 kOe, as expected of Eu2+ free ions. The magnetic phase diagram for H ∥ b in EuNiIn4 was found to have unique characteristics with five magnetic states in low magnetic fields.
