Magnetic ground state and perturbations of the distorted kagome Ising metal TmAgGe

C. LARSEN; D. G. MAZZONE; N. GAUTHIER; H. D. ROSALES; F. A. GÓMEZ ALBARRACÍN; J. LASS; X. BORALEY; S. L. BUD'KO; A. P. MACKENZIE; O. ZAHARKO

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2023

1098-0121

We present the magnetic orders and excitations of the distorted kagome intermetallic magnet TmAgGe. Using neutron single crystal diffraction we identify the propagation vectors k = ( 1/2 0 0) and k = (0 0 0) and determine the magnetic structures of the zero-field and magnetic field-induced phases for H along the a and [−110] crystal directions. We determine the experimental magnetic field- temperature (H, T )-phase diagram and reproduce it by Monte-Carlo simulations of an effective spin exchange Hamiltonian for one distorted kagome layer. Our model includes a strong axial single-ion anisotropy and significantly smaller exchange couplings which span up to the third-nearest neighbours within the layer. Single crystal inelastic neutron scattering (INS) measurements revealan almost flat, only weakly dispersive mode around 7 meV that we use alongside bulk magnetization data to deduce the crystal-electric field (CEF) scheme for the Tm3+ ions. Random phase approximation (RPA)  calculations based on the determined CEF wave functions of the two lowestquasi-doublets enable an estimation of the interlayer coupling that is compatible with the experimental INS spectra. No evidence for low-energy spin waves associated to the magnetic order was found, which is consistent with the strongly Ising nature of the ground state.