Incommensurate antiferromagnetic structures in NdIn 3

Abstract

Among the AuCu 3-type RIn 3 series where R is a rare earth, the NdIn 3 compound presents a complex magnetic phase diagram. In this compound, which orders antiferromagnetically at T N = 5.9 K, three magnetic phases are separated by two sharp first-order transitions. The phase diagrams, determined for the main crystallographic directions, by magnetization measurements in fields up to 7 T show a strong dependence of the transition temperatures. In order to determine the actual magnetic structures in NdIn 3, a neutron diffraction experiment has been performed on a single crystal under magnetic field. It shows that the magnetic structures are collinear (single q ) with the magnetic moments aligned along the fourfold axis. They clearly evidence the existence of two incommensurate phases with q = ( 1 2 , 1 2 , τ) : for T N ⪰ T 5.5 K, τ 1 ≈ 0.037 2π a and the structure is sine-wave modulated, for 5.5 K > T > 4.7 K, τ 2 = 0.017 2π a and the structure squares up. Below 4.7 K the q = ( 1 2 , 1 2 , 0) commensurate structure is stabilized.