The influence of magnetic sublattice dilution on magnetic order in CeNiGe₃and UNiSi₂

Abstract

Polycrystalline samples of the Y-diluted antiferromagnet CeNiGe(3) (T(N) = 5.5 K) and Th-diluted ferromagnet UNiSi(2) (T(C) = 95 K) were studied by means of x-ray powder diffraction, magnetization and specific heat measurements performed in a wide temperature range. The lattice parameters of the Ce(1-x)Y(x)NiGe(3) alloys decrease linearly with increasing Y content, while the unit cell volume of U(1-x)Th(x)NiSi(2) increases linearly with increasing Th content. The ordering temperatures of the systems decrease monotonically with increasing x down to about 1.2 K in Ce(0.4)Y(0.6)NiGe(3) and 26 K in U(0.3)Th(0.7)NiSi(2), forming a dome of long-range magnetic order on their magnetic phase diagrams. The suppression of the magnetic order is associated with distinct broadening of the anomalies at T(N,C) due to crystallographic disorder being a consequence of the alloying. Below the magnetic percolation threshold x(c) of about 0.68 and 0.75 in the Ce- and U-based alloys, respectively, the long-range magnetic order smoothly evolves into a short-range one, forming a tail on the magnetic phase diagrams. The observed behaviour of Ce(1-x)Y(x)NiGe(3) and U(1-x)Th(x)NiSi(2) is characteristic of diluted magnetic alloys.

Effect of nickel substitution on magnetism in the layered van der Waals ferromagnet Fe3GeTe2

“…For example, the FM transition can become first order, develop a spin-density wave order and exhibit tricritical wings in a magnetic field, and in some cases even develop unconventional superconductivity. In contrast, in FM systems where either intrinsic disorder is present or FM is suppressed with chemical substitution (Sr 1−x Ca x RuO 3 8 , UNi 1−x Co x Si 2 9 , U 1−x Th x NiSi 2 10 ), the suppression of FM order often results in a smeared QPT after which the system goes into a short range spin glass freezing. In other disordered systems such as CePd 1−x Rh x and Ni 1−x V x were shown to exhibit a quantum Griffiths region near the FM QCP.…”