Enhancement of the effective mass at high magnetic fields in CeRhIn5

Abstract

The Kondo-lattice compound CeRhIn5 displays a field-induced Fermi surface reconstruction at B * ≈ 30 T, which occurs within the antiferromagnetic state, prior to the quantum critical point at Bc0 ≈ 50 T. Here, in order to investigate the nature of the Fermi surface change, we measured the magnetostriction, specific heat, and magnetic torque of CeRhIn5 across a wide range of magnetic fields. Our observations uncover the field-induced itineracy of the 4f electrons, where above Bonset ≈ 17 T there is a significant enhancement of the Sommerfeld coefficient, and spin-dependent effective cyclotron masses determined from quantum oscillations. Upon crossing Bonset, the temperature dependence of the specific heat also shows distinctly different behavior from that at low fields. Our results indicate that the Kondo coupling is remarkably robust upon increasing the magnetic field. This is ascribed to the delocalization of the 4f electrons at the Fermi surface reconstruction at B * . 1 G. R. Stewart, Non-Fermi-liquid behavior in d-and felectron metals. Rev. Mod. Phys. 73, 797 (2001).

Specific heat of CeRhIn$_5$ in high magnetic fields: Magnetic phase diagram revisited

“…Figure 3 shows the temperature dependence of the specific heat divided by temperature, C/T , obtained using the relaxation technique at different magnetic fields applied along the c axis. For this orientation of the magnetic field, T N is gradually suppressed, consistent with previous reports [6,12,13]. This is the usual behavior observed in AFM heavy-fermion compounds.…”

“…When a magnetic field is applied along the c axis, T N monotonically decreases until it is completely suppressed at B c ∼ 50 T [12,13]. Surprisingly, the critical field for this orientation is approximately the same as along the a axis in spite of a considerable crystallographic and magnetic anisotropy of CeRhIn 5 .…”

“…Surprisingly, the critical field for this orientation is approximately the same as along the a axis in spite of a considerable crystallographic and magnetic anisotropy of CeRhIn 5 . On the other hand, the critical field was extrapolated from specific heat measurements in pulsed magnetic fields, while there is a difference between the results obtained in pulsed [12,13] and static [6] fields.…”

“…While it was interpreted as a transition into an electronicnematic state [15], the exact origin and nature of this anomaly is still under debate. Surprisingly, specific heat measurements have so far failed to show a direct indication of this anomaly [6,12,13]. It is thus still unclear whether the anomaly corresponds to a real thermodynamic phase transition or a crossover.…”

Non-monotonic pressure dependence of high-field nematicity and magnetism in CeRhIn5

“…Recently, a field-induced phase transition was observed at intermediate magnetic fields B * ≥ 28 T 12,15,16 , and a nematic character of this high-field phase has been reported, based on the sudden emergence of an in-plane resistivity anisotropy 13 . Magnetic probes, such as magnetization and torque, however, show hardly any features in the relevant field-temperature range 13,14 , thus rendering a metamagnetic origin of the B * transition unlikely.…”