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Tetragonal UPt2Si2 has recently been characterized as moderately mass enhanced
antiferromagnetic compound, which in various physical properties reveals a resemblance to
the hidden order material URu2Si2 [1,2]. To further characterize this resemblance we
have examined UPt2Si2 with resistivity measurements in magnetic fields and deduce the
magnetic phase diagram. In particular, we find the antiferromagnetic phase transition at
TN=32K in zero field to shift slightly downwards to 31 K at B = 9 T || c-axis. Further,
the temperature dependence of the resistivity in the range up to 20K can be described by
an opening of a spin excitation gap. In contrast to TN this gap displays a much larger
reduction by about 30% with increasing magnetic field up to 9T. We discuss the
relationship between spin excitation gap and magnetic ordering, this in particular with
respect to the difference in field response.
[1] S. Süllow, A. Otop, A. Loose, J. Klenke, O. Prokhnenko, R. Feyerherm, R.W.A. Hendrikx, J.A. Mydosh, H. Amitsuka, J. Phys. Soc. Jpn. 77 (2008) 024708 [2] N. Johannsen, S. Süllow, A.V. Sologubenko, T. Lorenz, J.A. Mydosh, Phys. Rev. Lett., submitted (2008) |
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