4 pin inductor for buck convertor
That is likely to be not a suitable inductor for a buck switching regulator. It's a common mode choke and has two coils - it is intended for suppressing emissions amongst other things and not the best choice for your application. It will likely saturate if you try to use one of the windings (the other being superfluous in a buck circuit). With saturation comes poor efficiency and overheating. What does the manufacturer of the chip (buck regulator) recommend?