Enhanced Néel-Type Skyrmion Stability in Polar VOSe₂O₅ through Tunable Magnetic Anisotropy under Pressure

Hung-Cheng Wu^1*

¹Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan

* Presenter:Hung-Cheng Wu, email:tedwu@mail.nsysu.edu.tw

Polar VOSe2O5, belonging to the P4cc space group (C4V symmetry), was recently discovered to host a rare Néel-type skyrmion phase within a very narrow range of temperature and magnetic field. Motivated by this discovery, we investigated the effect of pressure on its magnetic properties, focusing on improving the stability of the skyrmion phase. At ambient pressure, two magnetic transitions were observed at TC1 ~ 7.4 K and TC2 ~ 4.0 K. Notably, the contrasting behavior of these transitions under applied magnetic fields—TC1 increases, whereas TC2 is suppressed—reflects the magnetic anisotropy in VOSe2O5. Neutron diffraction refinements revealed a three-up-one-down ferrimagnetic configuration aligned along the b-axis at 1.8 K, and an incommensurate cycloidal spin structure rotating within the bc-plane at 6 K, further demonstrating the intrinsic magnetic anisotropic in VOSe2O5. Pressure-dependent AC susceptibility measurements showed TC1 increasing by 0.043(3) K/kbar and TC2 decreasing by −0.052(4) K/kbar, indicating pressure-tunable anisotropy. The field−temperature (H−T) phase diagram confirms the stabilization of the Néel-type skyrmion phase under 14.21 kbar of pressure, with its area expanding approximately threefold. These findings underscore the role of pressure in promoting Néel-type skyrmion stability through modulation of the magnetic anisotropy, offering valuable insights into tuning topological phases for spintronics and related technological applications.

Keywords: Néel-Type Skyrmion, Magnetic anisotropy, Pressure effect, Neutron diffraction , AC susceptibility