Magnetic properties and quadrupolar interactions in PrAg

We present an extensive study of the cubic (CsCl-type) rare-earth intermetallic compound PrAg. Numerous experiments have been performed on poly- and monocrystalline samples: neutron spectroscopy, neutron-diffraction, neutron depolarization, resistivity, magnetization, and first- and third-order magnetic susceptibility measurements. Previous determinations of the crystal-field parameters and of the antiferromagnetic structure ($T_N=10.5\mathrm{}$ K) are well confirmed. However, neutron-diffraction and depolarization experiments as well as magnetization curves show the existence of an additional weak ferromagnetic component below $T_c=6.9\mathrm{}$ K. On the other hand, third-order magnetic susceptibility measurements along [001] and [111] axes have been analyzed within an analytical formalism: They reveal the presence of strong negative quadrupolar interactions, which favor a noncollinear arrangement for the magnetic moments.