We have performed precise dc magnetization measurements for a single crystal of UBe₁₃ down to 0.14 K, up to 80 kOe. We observed a magnetic anomaly in the superconducting (SC) mixed state at a field, named H_Mag^* (∼26  kOe, at 0.14 K), implying that UBe₁₃ has a magnetically unusual SC state. We expect that the origin of the H_Mag^* anomaly would be (1) unusual SC diamagnetic response, or (2) a peculiarity of the normal-state magnetization due to vortices in the SC mixed state.
For more information please see our paper: Y. Shimizu et al., Phys. Rev. Lett. 109 (2012) 217001.
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