The two-dimensional triangular lattice (TAL) is a model system of magnetic frustration and competing interactions, where skyrmion spin vortices can be induced by a vertical magnetic field B. We target the binary compound GdGa2 with an undistorted TAL of Gd3+ Heisenberg moments. At higher temperature (T>5 K, B=0, phase II), we reveal the cycloidal spin textures in GdGa2 via resonant elastic X-ray scattering (REXS). Further, a transition with strong magneto-elastic response occurs when cooling into the zero-field ground state (T<5 K, phase I). We also report the thermodynamic phase boundaries of B-induced magnetic A-phases, which are suppressed by an in-plane magnetic field and which have enhanced resistivity due to the partial opening of a charge gap. In analogy to Gd2PdSi3 and GdRu2Si2, these phases may represent a superposition of various cycloids, possibly a N\'eel skyrmion lattice. Our work lays the basis for further studies of the magnetic phase diagram of GdGa2.
@article{arxiv.2503.18457,
title = {Triangular lattice magnet GdGa$_2$ with short-period spin cycloids and possible skyrmion phases},
author = {Priya R. Baral and Nguyen Duy Khanh and Masaki Gen and Hajime Sagayama and Hironori Nakao and Taka-hisa Arima and Yoshichika Ōnuki and Yoshinori Tokura and Max Hirschberger},
journal= {arXiv preprint arXiv:2503.18457},
year = {2025}
}