The presence of frustration and disorder are necessary ingredients for an SG transition. It was therefore surprising that PrAu₂Si₂ was reported to show all the characteristics of a SG, even though it is a stoichiometric compound with a well-ordered structure. To understand the origin of the SG ground state in PrAu₂Si₂, we have performed inelastic neutron scattering measurements of the crystal field (CF) excitation spectrum. These measurements classified PrAu₂Si₂ as an induced moment SG where the exchange interaction is only just above the critical value for induced moment magnetism with substantial CF linewidth at T_g which plays a central role in disrupting of induced moment formation (see figure) and resulting in the SG ground state. We suggest that PrAu₂Si₂ reveals a new way to achieving frustration in systems with neither static disorder nor geometrically frustrated lattices, through dynamic fluctuations in proximity to a critical phase boundary.

EA Goremychkin, DT Adroja (ISIS), R Osborn (ANL, USA), B Rainford (University of Southampton), M Koza (ILL, France)

Research date: December 2007

Further Information

EA Goremychkin et al, J. Mag. Mag. Mat. 310 (2007) 1535​