Magnetic Ordering of RAgSb₂Compounds

Abstract

The magnetic structures of the polycrystalline samples of RΑgSb 2 (R = Ce, Pr, Nd, Tb-Tm) are determined. All compounds crystallize in the tetragonal ΖrCuSi 2 -type of crystal structure and except CeΑgSb 2 they are antiferromagnets with a Neel temperature of 11 Κ for R = Tb and 2 Κ for Tm. CeΑgSb2 below Tc = 9.5 Κ is ferromagnet with the magnetic moment eqnal to 0.33μB and parallel to c-axis. In NdAgSb 2 the sine modulated magnetic ordering described by the wave vector k = (0.5435,0,0) is observed. Below TN a collinear antiferromagnetic structure with the magnetic (a, a, 2c) for R = Pr and (2a, a, c) for R = Tb, Dy, Ho, and Er is observed. For Ho-compound with an increase in temperature the coexistence of two strnctures is observed: commensurate collinear and incommensurate sine modulated. In TmAgSb2 the coexistence of the two phases is observed at Τ = 1.4 K. With an increase in temperature only the incommensurate phase stays.PACS numbers: 75.30.Cr, 75.30.Kz, 75.50.Εe 1. Introduction In the framework of our systematic studies of the magnetic properties of the rare-earth intermetallic compounds we present results of the neutron diffraction measurements of RΑgSb2 compounds, where R = Ce-Nd, Tb-Tm in this work. Recently we have reported on the structure and magnetic properties of ternary rare-earth RΑgSb 2 compounds. X-ray powder diffraction data indicate that these compounds crystallize in the tetragonal ΖrCuSi2-type structure (space group P4/nmm) [1]. RΑgSb 2 compounds, with R = Pr, Nd, Sm, Gd, Dy, Ho, Er, and Tm are antiferromagnets with the Néel temperatures lower than 13 K [1]. CeΑgSb2 is a ferromagnet with Τ = 12 [1] or 10 K [2]. In this work we present the results of the neutron diffraction measurements undertaken in order to determine the crystal and magnetic structures of RΑgSb2 compounds (R = Ce, Pr, Nd, Tb-Tm).

Crystal and magnetic structures of RCuSb2 (R = Dy, Ho) compounds

“…From the magnetic data for the isostructural RAgSb 2 compounds the B 0 2 parameter is positive for R = Tb−Ho and negative for R = Er and Tm [17]. In the TbTSb 2 family of compounds the direction of the magnetic moment changes from the parallel to the c-axis for T = Ni and Pd to the perpendicular to it for R = Cu and Ag [6][7][8][9][10][11][12]. Similar change of the direction of the magnetic moment is observed in RT 2 Si 2 compounds which crystallize in the tetragonal crystal structure.…”

“…The RTSb 2 rare earth compounds (R = rare earth element and T = d-electron element) have been reported to have various magnetic structures and interesting magnetic properties [1][2][3][4][5][6][7][8][9][10][11][12]. X-ray and neutron diffraction indicate that these compounds crystallize in the tetragonal ZrCuSi 2 -type of structure (space group P4/nmm).…”