Pressure dependence of the magnetic properties and phase diagram of HoCo12B6 ferrimagnetic compound

The magnetic properties of HoCo ₁₂B ₆ ferrimagnetic compound are investigated versus the magnetic field, temperature and pressure. The magnetic phase diagram exhibits three remarkable temperatures: the ordering temperature T _C, the spin reorientation temperature T _SR and the compensation temperature T _COMP at 147 K, 76 K and 47 K respectively. In HoCo ₁₂B ₆ intermetallic system the spontaneous magnetization resulting from the antiparallel coupling of the magnetic moments of Ho and Co sublattices is pressure insensitive at lowest temperatures whereas it decreases with pressure at temperature range above T _SR. The mean Co magnetic moment is small (<0.5 µ _B) in the studied compound and exhibits a weak pressure dependence. In addition, significant pressure effects have been observed on both the spin reorientation transition and the Curie temperatures. A value of dT _C/dp = −3.5 ± 0.4 K GPa ⁻¹ is dominated by the Co sublattice contribution. The spin reorientation transition temperature is also found to decrease versus pressure dT _SR/dp = −4.2 ± 0.4 K GPa ⁻¹. The compensation temperature where the Ho and Co sublattices have the same magnitude but opposite direction does not vary significantly with applied pressure in the investigated pressure range (up to 1 GPa). The results of pressure dependence of the magnetic properties are compared to earlier results on other R-Co-B borides. HoCo ₁₂B ₆ compound confirmed the remarkably high volume stability of the magnetic properties of the RCo ₁₂B ₆ compounds with the itinerant character of magnetism and low values of both the T _C and magnetization.