Structural stability and magnetic properties of LnMxGa3 (Ln = Ho, Er; M = Fe, Co; x < 0.2)

Abstract

Single crystals of LnMxGa3 (Ln=Ho, Er; M=Fe, Co; x<0.2) were grown from a Ga self-flux. The compounds crystallize in a “stuffed” variant of the AuCu3-structure type where Fe or Co partially occupies the body-centered position of the unit cell surrounded by six Ga atoms. The insertion of Fe or Co guest atoms into the AuCu3-structure type causes a structural change in the host material where chemical pressure is exerted on Ga–Ga contacts surrounding the filled octahedra. This in turn affects the stability of the AuCu3-structure type and the intrinsic properties of the materials. With increasing Ho–Ho distances of 4.2355(5), 4.2377(5), and 4.2441(3)Å, HoCo0.16(2)Ga3, HoFe0.11(1)Ga3, and HoFe0.16(2)Ga3 order antiferromagnetically with decreasing Néel temperatures of TN=10.2, 7.2, and 6.5K, respectively. ErCo0.06(2)Ga3, ErFe0.06(1)Ga3, and ErFe0.11(2)Ga3 order antiferromagnetically with Néel temperatures of TN=3.3, 5.2, and 6.2K. The magnetic properties are attributed to changes in the coupling strength of local magnetic moment with conduction electrons as a function of transition metal and rare earth.