High pressure effects on magnetic states of elemental holmium

•Suppression of the low temperature cone structure under pressure.•Rapid pressure-induced increase of the lock-in transition temperature.•Significant increase of commensurate qz component of the helical structure up to ¼ c* below the lock-in transition.•Magnetic P-T phase diagram of elemental Ho. The pressure response of the magnetic and structural properties of elemental holmium was explored by means of neutron powder diffraction in the pressure range up to 8.7 GPa and the temperature range 7 – 290 K. At ambient pressure, below TN = 127 K the incommensurate helical state with a propagation vector q = (0 0 qz) is evidenced. On temperature lowering, the qz value decreases from 0.270c* (at 125 K) to 5/26c* at TL = 20 K. Below the lock-in transition temperature TL, a commensurate cone structure is formed due to canting of magnetic moments towards the c axis. Upon lattice compression, a gradual suppression of the low temperature cone structure was found and just a helical state was observed above 4 GPa. This state is incommensurate in the temperature range TL