title: Thermodynamic Measurement of Angular Anisotropy at the Hidden Order Transition of URu_{2}Si_{2}.
abstract: The heavy fermion compound URu_{2}Si_{2} continues to attract great interest due to the unidentified hidden order it develops below 17.5 K. The unique Ising character of the spin fluctuations and low-temperature quasiparticles is well established. We present detailed measurements of the angular anisotropy of the nonlinear magnetization that reveal a cos^{4}θ Ising anisotropy both at and above the ordering transition. With Landau theory, we show this implies a strongly Ising character of the itinerant hidden order parameter.
authors: Physics Department, University of California Santa Cruz, Santa Cruz, California 95064, USA.
authors: Jennifer
authors: J
authors: Trinh
authors: Fundamental Aspects of Materials and Energy, Faculty of Applied Sciences, TU Delft Mekelweg, 15, 2629 JB Delft, Netherlands.
authors: Ekkes
authors: E
authors: Brück
authors: National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.|Department of Chemistry and Biomedical Engineering, Florida State University, Tallahassee, Florida 32310, USA.
authors: Theo
authors: T
authors: Siegrist
authors: Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors: Rebecca
authors: R
authors: Flint
authors: Center for Materials Theory, Rutgers University, Piscataway, New Jersey 08854, USA.
authors: Premala
authors: P
authors: Chandra
authors: Center for Materials Theory, Rutgers University, Piscataway, New Jersey 08854, USA.|Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom.
authors: Piers
authors: P
authors: Coleman
authors: Physics Department, University of California Santa Cruz, Santa Cruz, California 95064, USA.
authors: Arthur P
authors: AP
authors: Ramirez