Emergent magnetic anisotropy in the cubic heavy-fermion metal CeIn 3

Metals containing cerium exhibit a diverse range of fascinating phenomena including heavy fermion behavior, quantum criticality, and novel states of matter such as unconventional superconductivity. The cubic system CeIn3 has attracted significant attention as a structurally isotropic Kondo lattice material possessing the minimum required complexity to still reveal this rich physics. By using magnetic fields with strengths comparable to the crystal field energy scale, we illustrate a strong field-induced anisotropy as a consequence of non-spherically symmetric spin interactions in the prototypical heavy fermion material CeIn3. This work demonstrates the importance of magnetic anisotropy in modeling f-electron materials when the orbital character of the 4f wavefunction changes (e.g., with pressure or composition). In addition, magnetic fields are shown to tune the effective hybridization and exchange interactions potentially leading to new exotic field tuned effects in f-based materials. Magnetic anisotropy emerges in structurally isotropic heavy fermion metals under large magnetic fields. Compounds that contain rare earth or actinide ions with unpaired f-electrons can exhibit a range of fascinating phenomena, such as heavy fermion behaviour. The role of magnetic and electronic anisotropies is often crucial for understanding the rich physics of these materials, but it can often be difficult to disentangle the contributions from structural anisotropies. An international team of researchers led by Philip Moll from the Max-Planck-Institute for Chemical Physics of Solids now show that when magnetic fields are applied, with strengths similar to the crystal fields, magnetic anisotropies can emerge in cubic f-electron materials that are structurally isotropic. They show that this arises from non-spherically symmetric spin interactions, which exposes failures of the spherically symmetric models often used to describe these systems.