Magnetic structure of ${\mathrm{HoBe}}_{13}$ in an applied magnetic field

The magnetic structure of ${\mathrm{HoBe}}_{13}$ and its evolution under an applied magnetic field have been examined using neutron diffraction and bulk magnetization measurements on a single crystal. In the absence of an external field this cubic compound orders at $T_N=5.7\mathrm{}\left(1\right)\mathrm{}\mathrm{K}$ into a regular helical magnetic structure with propagation vector $\mathbf{k}=\left[00\frac{1}{3}\right].$ Third-order harmonics appear at 4.4(1) K and are attributed to a deformation of the helical structure below this temperature. When a magnetic field is applied along a [001] axis two magnetic transitions occur. First the magnetic domain with propagation vector parallel to the field is favored and, with the addition of the induced ferromagnetic component, by about 4 kG we have a single-domain conical structure. The surprising observation was that at higher fields (15 kG at 1.4 K) the other two domains reappear and become the preferred ones. This reentrant behavior is due to the change of the magnetic structure to a canted arrangement, involving a ferromagnetic component along the applied field and a transverse collinear antiferromagnetic component. When the magnetic field is applied along a [110] axis only one transition is observed from the helical to the conical structure. The magnetic phase diagram of ${\mathrm{HoBe}}_{13}$ has been constructed.