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arXiv · 2503.18457

Triangular lattice magnet GdGa$_2$ with short-period spin cycloids and possible skyrmion phases

Priya R. Baral·Nguyen Duy Khanh·Masaki Gen·Hajime Sagayama·Hironori Nakao·Taka-hisa Arima·Yoshichika Ōnuki·Yoshinori Tokura·Max Hirschberger
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Abstract

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 GdGa$_2$ with an undistorted TAL of Gd$^{3+}$ Heisenberg moments. At higher temperature ($T > 5$ K, $B = 0$, phase II), we reveal the cycloidal spin textures in GdGa$_2$ 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 Gd$_2$PdSi$_3$ and GdRu$_2$Si$_2$, 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 GdGa$_2$.

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Priya R. Baral, Nguyen Duy Khanh, Masaki Gen, Hajime Sagayama, Hironori Nakao, Taka-hisa Arima, Yoshichika Ōnuki, Yoshinori Tokura, Max Hirschberger. 2025-03-24. Triangular lattice magnet GdGa$_2$ with short-period spin cycloids and possible skyrmion phases. https://doi.org/10.7566/jpsj.94.024705

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