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The low temperature antiferromagnet (T_N = 32 K) UPt₂Si₂ exhibits complex magnetic field-induced phases. Previous studies have established magnetic phase diagrams for applied fields along the a- and c-axes and suggest that the metamagnetic phase transitions (PT) may be associated with an evolution of the Fermi surface [1,2]. Here, we examine the PT angle dependence with RF skin depth and torque magnetometry experiments at temperatures T < 1 K and in fields H < 45 T. We find that AFMI → III evolves with nearly 1/cosθ dependence, III → V is hysteretic and nearly angle independent, and an additional PT in region V that also follows a 1/cosθ dependence. We shall discuss these results and the implications for the metamagnetism in UPt₂Si₂ and similar uranium-based materials.
[1] Grachtrup et al., Phys. Rev. B 85, 054410 (2012)
[2] Grachtrup et al., Phys. Rev. B 95, 134422 (2017)