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Abstract:
We present measurements of the magnetization M, specific heat C,
resistivity., and magnetoresistance MR of single-crystalline hexagonal
CeAuSn for temperature down to T = 1.6 K and in magnetic field up to B =
12 T. Antiferromagnetic ordering at T-N = 4.4 K is observed as
previously found for polycrystalline samples. A strong magnetic
easy-plane anisotropy of M for B perpendicular and parallel to the c
direction is found with M-perpendicular to/M-parallel to approximate to
15 in B = 0.1 T around T-N, which is attributed to
crystal-electric-field anisotropy. The analysis of the magnetic
susceptibility indicates ferromagnetic correlations above T-N.
Measurements of M(T) under hydrostatic pressure P show that T-N(P)
increases linearly with P at a small rate of 0.035 K/kbar up to 4 kbar
and gradually saturates approaching P = 16 kbar. Zero-field Delta C/T,
the phonon contribution to C being subtracted, is proportional to T-2
below T-N indicating a gapless spin-wave spectrum. It is found that all
Delta C(T,B)/T curves for B = 0-9 T cross at the same temperature,
providing an example of a particularly well defined isosbestic point in
a very narrow region around T-iso = 6.6 K. Finally, rho(T) and MR
experiments with current perpendicular and parallel to B allow us to
separate orbital effects from the Zeeman splitting.
