Low-temperature electron paramagnetic resonance measurements are performed on single crystals of LiY_{1-x}Gd_xF_4 with weak x=0.005 and moderate x=0.05 concentration of Gd ions. Modeling of the experimental spectra allows us to precisely determine microscopic parameters of the spin Hamiltonian of the parent LiGdF4 material, including the nearest-neighbor exchange constant. The obtained parameters are further tested by comparing a strongly anisotropic Curie-Weiss temperature obtained for LiGdF4 in our static magnetization measurements with theoretically computed values. We find a fine balance between principal magnetic interactions in LiGdF4, which results in a hidden magnetic frustration presumably leading to a delayed magnetic ordering and an enhanced magnetocaloric effect at low temperatures.
@article{arxiv.2210.09725,
title = {Microscopic spin Hamiltonian for a dipolar-Heisenberg magnet LiGdF4 from EPR measurements},
author = {S. S. Sosin and A. F. Iafarova and I. V. Romanova and O. A. Morozov and S. L. Korableva and R. G. Batulin and M. Zhitomirsky and V. N. Glazkov},
journal= {arXiv preprint arXiv:2210.09725},
year = {2023}
}