Search

The tetragonal compound UPt2SI2 has been characterized as a moderately mass-enhanced system with an anti-ferromagnetic (AFM) ground state below TN = 32 K. Here, we present an extensive study of the behavior in high magnetic fields. We have performed pulsed field magnetization and static field resistivity measurements on single crystalline samples UPt2SI2. Along the crystallographic a axis, at low temperatures, we find a metamagnetic-like transition in fields of the order 40 T, possibly indicating a first-order transition. Along the crystallographic c axis, in magnetic fields of B ≥ 24 T, we find distinct anomalies in both properties. From our analysis of the data we can distinguish new high-field phases above the AFM ground state. We discuss the emergence of these new phases in the context of Fermi surface effects and the possible occurrence of a Lifshitz or electronic topological transition, this in contrast to previous modelings of UPt2SI2 based on crystal electric field effects. [ABSTRACT FROM AUTHOR]

High field magnetization measurements have been performed on single crystalline tetragonal UPt2Si2 for the crystallographic a and c directions. These results are compared to previous experiments and calculations based on a crystal electric field scheme. Our analysis indicates that the magnetization, while reproducing previous measurements, strongly deviates from the predictions of the crystal electric field scheme model for both crystallographic directions. This finding indicates that the magnetic behavior of UPt2Si2 is more adequately described within an itinerant approach. [ABSTRACT FROM AUTHOR]

High field magnetization measurements have been performed on single crystalline tetragonal UPt2Si2 for the crystallographic a and c directions. These results are compared to previous experiments and calculations based on a crystal electric field scheme. Our analysis indicates that the magnetization, while reproducing previous measurements, strongly deviates from the predictions of the crystal electric field scheme model for both crystallographic directions. This finding indicates that the magnetic behavior of UPt2Si2 is more adequately described within an itinerant approach. [ABSTRACT FROM AUTHOR]

We have measured the Hall effect, magnetotransport, and magnetostriction on the field-induced phases of single-crystalline UPt2Si2 in magnetic fields up to 60 T at temperatures down to 50 mK, firmly establishing the phase diagram for magnetic fields B∥a and c axes. Moreover, for the B∥c axis we observe strong changes in the Hall effect at the phase boundaries. From a comparison to band structure calculations utilizing the concept of a dual nature of the uranium 5f electrons, we propose that these represent field-induced topological changes of the Fermi surface due to at least one Lifshitz transition. Furthermore, we find a unique history dependence of the magnetotransport and magnetostriction data, indicating that the proposed Lifshitz-type transition is of a discontinuous nature, as predicted for interacting electron systems. [ABSTRACT FROM AUTHOR]