Dilution induced magnetic localization in Rb(Co$_{1-x}$Ni$_{x}$)$_{2}$Se$_{2}$ single crystals

TL;DR

This study investigates how substituting Ni for Co in RbCo2Se2 induces a transition from itinerant to localized magnetism, revealing magnetic evolution and localization effects in the material.

Contribution

It provides experimental evidence of magnetic localization caused by Ni doping, showing a transition from ferromagnetic to antiferromagnetic and paramagnetic states in Rb(Co$_{1-x}$Ni$_{x}$)$_{2}$Se$_{2}.

Findings

Magnetic susceptibility indicates evolution from ferromagnetism to paramagnetism with Ni doping.

Neutron diffraction reveals A-type antiferromagnetic order in certain compositions.

Magnetic moments increase with Ni concentration, demonstrating localization effects.

Abstract

We report experimental studies on a series of Rb(Co$_{1-x}$Ni$_{x}$)$_{2}$Se$_{2}$ (0.02 $\leq x \leq $ 0.9) powder and single crystal samples using x-ray diffraction, neutron diffraction, magnetic susceptibility, and electronic transport measurements. All compositions are metallic and adopt the body-centered tetragonal structure with $I4/mmm$ space group. Anisotropic magnetic susceptibilities measured on single crystal samples suggest that Rb(Co$_{1-x}$Ni$_{x}$)$_{2}$Se$_{2}$ undergo an evolution from ferromagnetism to antiferromagnetism, and finally to paramagnetism with increasing Ni concentration. Neutron diffraction measurements on the samples with $x$ = 0.1, 0.4, and 0.6 reveal an $A$-type antiferromagnetic order with moments lying in the $ab$ plane. The moment size changes from 0.69 ($x=0.1$) to 2.80$\mu_B$ ($x=0.6$) per Co ions. Our results demonstrate that dilution of the magnetic Co ions by substitution of nonmagnetic Ni ions induces magnetic localization and evolution from itinerant to localized magnetism in Rb(Co$_{1-x}$Ni$_{x}$)$_{2}$Se$_{2}$.