Field-induced antiferroquadrupolar order in the heavy fermion superconductor PrOsSb

Kaneko, Koji   ; Metoki, Naoto   ; Matsuda, Tatsuma; Kuwahara, Keitaro*; Kogi, Masafumi*; Shiina, Ryosuke*; Mignot, J.-M.*; Gukasov, A.*; Bernhoeft, N.*

Neutron diffraction experiments under magnetic fields were carried out on the heavy fermion superconductor PrOsSb in order to reveal the origin of the field-induced ordered phase (FIOP) for [1,1,0]. The application of magnetic field induces the weak superlattice peaks with the ordering vector =(1,0,0) in FIOP, which is the same as for [0,0,1]. The observed superlattice reflections for [1,1,0] result from the antiferromagnetic component of +; the induced tiny antiferromagnetic moments orient parallel to the applied field. This result cannot be explained by magnetic interactions and strongly evidences the underlying AFQ order with as a primary order parameter. These facts clarify the dominant role of -type antiferroquadrupolar interaction in PrOsSb.