Quantum critical 5f-electrons avoid singularities in U(Ru,Rh)2Si2

TL;DR

This study investigates the quantum critical behavior of 5f-electrons in Rh-doped U(Ru,Rh)2Si2 near a magnetic field-induced transition, revealing similarities to Ce-based systems and evidence of orbital or quadrupolar order.

Contribution

It demonstrates that hybridized band models apply to U-based systems and uncovers a phase transition near Hm linked to strong 5f-lattice coupling, not observed in Ce analogs.

Findings

Evidence of a quantum critical point near Hm.

Presence of an ordered phase in U-based system near Hm.

Strong coupling of 5f orbitals to the lattice suggesting orbital or quadrupolar order.

Abstract

We present specific heat measurements of 4% Rh-doped U(Ru,Rh)2Si2 at magnetic fields above the proposed metamagnetic transition field Hm~34 T, revealing striking similarities to the isotructural Ce analog CeRu2Si2, suggesting that strongly renormalized hybridized band models apply equally well to both systems. The vanishing bandwidths as H --> Hm are consistent with a putative quantum critical point close to Hm. The existence of a phase transition into an ordered phase in the vicinity of Hm for 4% Rh-doped U(Ru,Rh)2Si2, but not for CeRu2Si2, is consistent with a stronger super-exchange in the case of the U 5-f system, with irreversible processes at the transition revealing a strong coupling of the 5f orbitals to the lattice, most suggestive of orbital or electric quadrupolar order.