Heavy fermions. Chirality density wave of the "hidden order" phase in URu₂Si₂

H-H Kung; R E Baumbach; E D Bauer; V K Thorsmølle; W-L Zhang; K Haule; J A Mydosh; G Blumberg

doi:10.1126/science.1259729

Heavy fermions. Chirality density wave of the "hidden order" phase in URu₂Si₂

Science. 2015 Mar 20;347(6228):1339-42. doi: 10.1126/science.1259729. Epub 2015 Feb 12.

Authors

H-H Kung¹, R E Baumbach², E D Bauer², V K Thorsmølle³, W-L Zhang³, K Haule¹, J A Mydosh⁴, G Blumberg⁵

Affiliations

¹ Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA. girsh@physics.rutgers.edu haule@physics.rutgers.edu skung@physics.rutgers.edu.
² Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
³ Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA.
⁴ Kamerlingh Onnes Laboratory, Leiden University, 2300 RA Leiden, Netherlands.
⁵ Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA. National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia. girsh@physics.rutgers.edu haule@physics.rutgers.edu skung@physics.rutgers.edu.

PMID: 25678557
DOI: 10.1126/science.1259729

Abstract

A second-order phase transition in a physical system is associated with the emergence of an "order parameter" and a spontaneous symmetry breaking. The heavy fermion superconductor URu2Si2 has a "hidden order" (HO) phase below the temperature of 17.5 kelvin; the symmetry of the associated order parameter has remained ambiguous. Here we use polarization-resolved Raman spectroscopy to specify the symmetry of the low-energy excitations above and below the HO transition. We determine that the HO parameter breaks local vertical and diagonal reflection symmetries at the uranium sites, resulting in crystal field states with distinct chiral properties, which order to a commensurate chirality density wave ground state.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.