I'd like to build an electromagnet coil that's capable of re-magnetizing (Changing the magnetic field direction) AlNiCo500 (LNG44, Hc=50 kA/m). But failed. The Magnet is is 3mm in diameter and 12mm in length. In the beginning, I used a H-Bridge circuit to do that, shown in the attached thumbnail, the voltage is 20v, but it didn't work. I thought maybe my coil is not thick enough, so I made another one.It didn't work too. Finally, I directly use my hand to quickly add a 20V voltage on each side of the coil to make a pulse, but it still didn't work. The coil was getting very hot. I don't know why. So I ask your help.