Anisotropic electronic and magnetic properties of the quasi-two-dimensional heavy-fermion antiferromagnet CeRhIn5

We have used high pulsed magnetic fields to 50 T to observe de Haas-van Alp hen oscillations in the tetragonal antiferromagnet CeRhIn5, which has an en hanced value of the electronic specific heat coefficient gamma greater than or similar to 420 mJ/mol K-2. For T<T-N, the specific heat data at zero ap plied magnetic field are consistent with the existence of an anisotropic sp in-density wave opening a gap in the Fermi surface. The low-temperature mag netization reveals a magnetic phase transition that appears to be first ord er in nature. Quantum oscillations, which are observed for T<T-N when B par allel to [100] and B parallel to [001], reveal an anisotropic Fermi surface . The temperature dependence of the amplitudes of the quantum oscillations shows anomalous behavior for B parallel to [001] as a maximum at T*approxim ate to1.2 K is observed which we attribute to a gap opening in the anisotro pic Fermi surface. The electronic and magnetic properties are anisotropic d ue to the quasi-two-dimensional crystal structure.