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Hastatic order in the heavy-fermion compound URu2Si2
Premala Chandra1, Piers Coleman, Rebecca Flint
1Center for Materials Theory, Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854-8019, USA.
Nature
|February 1, 2013
Summary
Researchers identified a novel
Area of Science:
- Condensed Matter Physics
- Quantum Materials
- Heavy Fermion Systems
Background:
- Collective long-range order arises from spontaneous symmetry breaking.
- Magnetism and superfluidity are linked to broken time-reversal and gauge symmetries, respectively.
- The symmetry breaking in URu2Si2 below 17.5 K remains unidentified.
Purpose of the Study:
- To identify the elusive broken symmetry in the heavy-fermion compound URu2Si2.
- To explain the origin of Ising quasiparticles observed in URu2Si2.
- To elucidate the nature of the phase transition at 17.5 K.
Main Methods:
- Theoretical analysis of order parameter symmetry.
- Investigation of electron hybridization.
- Interpretation of experimental observations like entropy of condensation and torque magnetometry.
Main Results:
- A spinor order parameter breaking double time-reversal symmetry ('hastatic' order) is identified.
- This hastatic order mixes integer and half-integer spin states.
- It hybridizes conduction electrons with Ising 5f(2) states, forming Ising quasiparticles.
Conclusions:
- Hastatic order explains the observed Ising quasiparticles and associated phenomena in URu2Si2.
- It accounts for the large entropy of condensation and magnetic anomalies.
- The theory predicts unique experimental signatures, including transverse moments, colossal Ising anisotropy, and resonant nematicity.
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