Symmetry Breaking in a Frustrated Heisenberg Spin System, ZnCr2O4: II. Neutron Scattering Measurements

Motivated by recent magnetic anisotropy measurements, we performed neutron scattering experiments for a single crystal of a typical geometrical frustration system (ZnCr 2 O 4 ) under a magnetic field. The magnetic structure of ZnCr 2 O 4 is easily affected by the applied magnetic field of about 2 T. The ( h h 0) ( h = n /2, n =odd) series magnetic Bragg peaks disappear when the magnetic field is applied along the [111] axis. It means that the magnetic structure turns into a new structure with higher symmetry than that in the ground state under a small magnetic field.