High-field magnetization study of a Tm₂Co₁₇ single crystal

Tm₂Co₁₇ is a ferrimagnet with T_C = 1170 K and, at 4.2 K, has a spontaneous magnetic moment M_s =13.4 mu_B/ f.u. Magnetization curves were measured on a Tm₂Co₁₇ single crystal along the principal axes in pulsed magnetic fields up to 70 T at 4.2 K. The curve along the easy [001] direction exhibits a distinct anomaly at mu₀H_cr = 39 T, where the magnetization exhibits a stepwise rise from M_s to M_flip = 40.6 mu_B/ f.u. The observed transition from the ferrimagnetic ground state (with M_s = 17mu_Co − 2mu_Tm) to a saturated spin-flip state with parallel orientation of the sublattice moments and M_flip = 17mu_Co + 2mu_Tm is unusual for 3d-4f intermetallics because it does not proceed via an intermediate angled-sublattice state. Rather, a collinear remagnetization of the Tm sublattice takes place: as the applied magnetic field grows, the Tm moments disorder at first, reaching a fully disordered paramagnetic state at H = H_cr, then they order magnetically in the opposite sense.