Abstract
Hidden-order phases that occur in a number of correlated f-electron systems are among the most elusive states of electronic matter. Their investigations are hindered by the insensitivity of standard physical probes, such as neutron diffraction, to the order parameter that is usually associated with higher-order multipoles of the f orbitals. The heavy-fermion compound Ce3Pd20Si6 exhibits magnetically hidden order at subkelvin temperatures, known as phase II. Additionally, for magnetic field applied along the [001] cubic axis, another phase II′ was detected, but the nature of the transition from phase II to phase II′ remained unclear. Here we use inelastic neutron scattering to argue that this transition is most likely associated with a change in the propagation vector of the antiferroquadrupolar order from (111) to (100). Despite the absence of magnetic Bragg scattering in phase II′, its ordering vector is revealed by the location of an intense magnetic soft mode at the (100) wave vector, that is orthogonal to the applied field. At the II-II′ transition, this mode softens and transforms into quasielastic and nearly Q-independent incoherent scattering, which is likely related to the non-Fermi-liquid behavior recently observed at this transition. Our experiment also reveals sharp collective excitations in the field-polarized paramagnetic phase, after phase II′ is suppressed in fields above 4 T.
Original language | English |
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Article number | 214431 |
Journal | Physical Review B |
Volume | 99 |
Issue number | 21 |
DOIs | |
State | Published - Jun 24 2019 |
Funding
Reduction of the TOF data was done using the Horace software package [40] . We acknowledge fruitful discussions with Q. Si and P. Thalmeier. D.S.I. also thanks M. Vojta for his helpful feedback on the original manuscript. This project was funded by the German Research Foundation (DFG) under Grant No. IN 209/3-2, via the project C03 of the Collaborative Research Center SFB 1143 (project-id 247310070) at the TU Dresden and the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter – ct.qmat (EXC 2147, project-id 39085490). S.E.N. acknowledges support from the International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM). A. Prokofiev and S.P. acknowledge financial support from the Austrian Science Fund (project P29296-N27). Research at Oak Ridge National Laboratory's Spallation Neutron Source was supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.