Magnetic field tuned superconducting and normal-phase magnetism in CeCo0.5Rh0.5In5

Abstract

By tuning the superconducting order parameter with an applied magnetic field, we use neutron diffraction to compare the magnetically ordered phases in superconducting and normal states of CeCo0.5Rh0.5In5. At zero applied field, CeCo0.5Rh0.5In5 displays both superconductivity (Tc=1.3K) and spatially long-ranged commensurate ↑↓↑↓ antiferromagnetism [TN=2.5K, propagation vector Q⃗=(12,12,12)]. Neutron spectroscopy fails to measure propagating magnetic excitations from this ground state with only temporally overdamped fluctuations observable. On applying a magnetic field which suppresses superconductivity, we find anisotropic behavior in the static magnetism. When the applied magnetic field is along the crystallographic c axis, no change in the static magnetic response is observable. However, when the field is oriented within the a−b plane, an increase in TN and change in the critical response are measured. At low temperatures in the superconducting phase, the elastic magnetic intensity increases linearly (∝|H|) with small a−b oriented fields. However, this trend is interrupted at intermediate fields where commensurate block ↑↑↓↓ magnetism with propagation vector Q⃗=(12,12,14) forms. For large applied fields in the [11¯0] direction which completely suppresses superconductivity, weakly incommensurate magnetic order along L is observed to replace the commensurate response present in the superconducting and vortex phases. We discuss experimental considerations related to this shift in momentum and suggest field-induced incommensurate static magnetism, present in the normal state of superconducting and antiferromagnetic CeCo0.5Rh0.5In5 for a−b plane oriented magnetic fields. We speculate that these field-dependent properties are tied to the field-induced anisotropy associated with the local Ce3+ crystal field environment of the tetragonal “115” structure.

Source-reported materials — not catalogue approval

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