Magnetic phase diagram ofα-NdIr2Si2

Abstract

Magnetism in $\ensuremath{\alpha}$-NdIr${}_{2}$Si${}_{2}$ single crystals has been probed through specific-heat, magnetization, magnetic susceptibility, and electrical resistivity measurements as a function of temperature, under an applied magnetic field, and for the magnetization curves under high hydrostatic pressures. Neutron diffraction experiments performed with powder and single-crystal samples were focused on microscopic aspects. Two collinear (Nd moments along the $c$ axis) antiferromagnetic phases are found at low temperatures: a longitudinal sine-modulated structure with the magnetic propagation vector k $=$ (0 0 5/6) at temperatures 18.2(2) K $lTl$ 32.3(3) K ($+{T}_{N}$) and a simple AF1-type structure; k $=$ (0 0 1/2) for $Tl$ 18.2(2) K ($+{T}_{t}$). Both of the magnetically ordered phases can be destabilized by applying a strong magnetic field along the $c$ axis. The character of the unusual magnetic-field-induced phases is discussed, and the complex magnetic phase diagram is constructed. Applied hydrostatic pressure yields an increase of both ${T}_{N}$ and ${T}_{t}$. The determined physical properties of $\ensuremath{\alpha}$-NdIr${}_{2}$Si${}_{2}$ are discussed in the context of behavior of $\ensuremath{\alpha}$-PrIr${}_{2}$Si${}_{2}$.