Neutron-Diffraction Study of Quadrupolar Order in TmTe: First Evidence for a Field-Induced Magnetic Superstructure

The intriguing phase transition discovered recently in TmTe at TQ0ex0ex=0ex0ex1.80ex0exK is characterized as antiferroquadrupolar by neutron diffraction. In an applied magnetic field, the underlying ordered structure of the Tm quadrupole moments is disclosed by the appearance of an antiferromagnetic component of the magnetic dipole moments. This induced structure is described by the wave vector k0ex0ex=0ex0ex(1/2,1/2,1/2) for both field directions H0ex0ex0ex0ex(111) and H0ex0ex0ex0ex(001), but the staggered component μAF, oriented along a twofold cubic axis normal to the field, is much stronger (about 1.5μB) in the former case.