1. A programmable circuit, comprising: a programmable fuse including; a magnetic tunnel junction (MTJ); a MTJ control circuit coupled to the MTJ to control the MTJ to cause a breakdown in the MTJ in programming the MTJ, thus forming a breakdown region with a low resistance; a sensing circuit coupled to the MTJ to sense a voltage under a breakdown condition of the MTJ; and wherein the magnetization of the MTJ is controlled by a current injected into the MTJ based on a spin-transfer torque effect.