Field-induced spin-density wave beyond hidden order in URu2Si2.

W Knafo,X Tonon,P Frings,E Lelièvre-Berna,F Duc,J Flouquet,J Billette,H Nojiri,L.-P Regnault,D Aoki,K Kuwahara,F Bourdarot

doi:10.1038/ncomms13075

Abstract

URu2Si2 is one of the most enigmatic strongly correlated electron systems and offers a fertile testing ground for new concepts in condensed matter science. In spite of >30 years of intense research, no consensus on the order parameter of its low-temperature hidden-order phase exists. A strong magnetic field transforms the hidden order into magnetically ordered phases, whose order parameter has also been defying experimental observation. Here, thanks to neutron diffraction under pulsed magnetic fields up to 40 T, we identify the field-induced phases of URu2Si2 as a spin-density-wave state. The transition to the spin-density wave represents a unique touchstone for understanding the hidden-order phase. An intimate relationship between this magnetic structure, the magnetic fluctuations and the Fermi surface is emphasized, calling for dedicated band-structure calculations.

Highlights

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In the hidden-order phase, the low-energy magnetic fluctuations are peaked at the hot wavevectors k0 and k1 1⁄4 (0.6 0 0)[7,8], and the Fermi surface presents nesting with these two wavevectors[9,10,11,12,13,14,15], suggesting an itinerant origin of the magnetic properties
By comparison with 3d itinerant magnets, a novelty in heavyfermion compounds is that a large magnetic polarization can be induced by a magnetic field, opening the path to new phases driven by combined changes of magnetic order and Fermi surface

Summary

Introduction

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. Quantum oscillations probes have shown that a magnetic field along c induces Fermi surface instabilities deep inside the hidden-order phase, as well as at the magnetic transitions H1, H2 and H3 (refs 24–28). By comparison with 3d itinerant magnets, a novelty in heavyfermion compounds is that a large magnetic polarization can be induced by a magnetic field, opening the path to new phases driven by combined changes of magnetic order and Fermi surface. Such interplay of metamagnetic and Lifshitz transitions has been evidenced in the heavy-fermion paramagnet CeRu2Si2 Such interplay of metamagnetic and Lifshitz transitions has been evidenced in the heavy-fermion paramagnet CeRu2Si2 (ref. 29)

Methods

Results

Conclusion