Anomalous superconducting phase diagram in UBe₁₃

UBe13 and U1−xThxBe13: Unconventional Superconductors

“…Shimizu et al [59] report an anomaly in their dc magnetization measurements in the superconducting state as a function of field (e. g. at 2.6 T and 0.14 K) that they are unable to explain. Magnetic torque measurements by Schmiedeshoff et al [60] also infer a field induced magnetic anomaly at low temperatures in UBe13 above 3-5 T, as well as in the normal state (i. e. inconsistent with the work of Shimizu et al) In agreement with the finding [35][36] of an anomaly below Tc in field, Matsuno et al [61] find an anomaly in single crystal UBe13 in the surface impedance below Tc at about 0.6Hc2.…”

“…The result of Rauchschwalbe et al [33], that there is an anomaly at about 0.5 Tc in zero field in UBe13unconfirmed despite there being many measurements of the specific heat of UBe13 in the literature -may be due to issues of sample purity. The issue of whether there is a magnetic field induced anomaly below Tc in pure UBe13 (as seen in specific heat by Ellman et al [35] and Kromer et al [36] and in various other measurements [59][60][61]) has been of sufficiently inconsistent nature that it has attracted no conclusive theoretical explanation and remains open for understanding.…”