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Theme 3 colloquium: “The mysterious high-field state of CeRhIn5: A microstructuring approach” (Lecture)

Tuesday 18 April 2017Add to my calendar
from 16:00
dr. Phillip Moll (Max Planck Institute Munchen, Germany)

Metals containing Ce exhibit rich physics due to their 4f electron, which can be both of local character acting as a localized magnetic moment; and hybridize with the conduction electrons to delocalize forming heavy quasiparticles, the so-called heavy fermions. Here I will discuss the high field state of CeRhIn5, which at ambient pressure and zero field hosts an anti-ferromagnetic order (AFM) of nominally localized 4f electrons at TN=3.8K(1). A dome of presumably d-wave superconductivity appears under pressure around a quantum critical point separating the low-pressure, local moment anti-ferromagnetic phase from the high-pressure, delocalized paramagnetic phase at pc=23kbar.

Alternatively, at ambient pressure the AFM order can also be suppressed by magnetic fields at a critical field Hc=50T, which is remarkably isotropic despite the anisotropy of the magnetic susceptibility at high fields(2). Unlike pressure, magnetic fields tend to localize the 4f electrons and thus the physical situation at the phase boundary is expected to be different in these two situations. Yet the phenomenology in high magnetic fields and under pressure shares nonetheless unexpected similarities. Similar to the dome of superconductivity, recently a correlated phase was discovered in fields larger than H*~28T as a dome connected to the field-induced quantum critical point at Hc(3, 4).

Here I will discuss our recent results probing the nature of this new high field phase, which uncovered an intriguing puzzle. This state is characterized by a very pronounced in-plane symmetry breaking observed in magnetotransport. Focused-ion-beam prepared microstructures probe the transport along orthogonal in-plane directions, which are symmetry equivalent in the tetragonal crystal structure. Yet at B*, we observe a first-order-like transition into a state of strongly anisotropic in-plane transport, with 𝜌𝜌𝑎𝑎𝜌𝜌𝑏𝑏⁄~10. At the same time, detailed measurements of the magnetization, the magnetic torque, heat capacity, out-of-plane transport, and dilatometry fail to detect the transition. These observations are at odds with previous ideas of field induced density wave order or metamagnetic reorientations. We propose to describe this exotic high field state in terms of an electronic nematic.

CeRhIn5 cooloquium theme 3 april17
CeRhIn5 microstructured single crystal for high-field experiments

1. H. Hegger et al., Pressure-induced superconductivity in quasi-2D CeRhIn5. Phys. Rev. Lett. 84, 4986–9 (2000).
2. T. Takeuchi, T. Inoue, K. Sugiyama, D. Aoki, Magnetic and Thermal Properties of CeIrIn 5 and CeRhIn 5. J. Phys. Soc. Japan. 70, 877–883 (2001).
3. L. Jiao et al., Fermi surface reconstruction and multiple quantum phase transitions in the antiferromagnet CeRhIn5. Proc. Natl. Acad. Sci. U. S. A. 112, 673–678 (2015).
4. P. J. W. Moll et al., Field induced density wave in the heavy fermion compound CeRhIn5. Nat. Commun. 6, 6663 (2015).

There will be an opportunity to discuss the colloquium and other developments during an informal get-together directly afterwards.

prof. Nigel Hussey