  Magnetic skyrmions are topological spin textures which are envisioned as
nanometre scale information carriers in magnetic memory and logic devices. The
recent demonstration of room temperature stabilization of skyrmions and their
current induced manipulation in industry compatible ultrathin films were first
steps towards the realisation of such devices. However, important challenges
remain regarding the electrical detection and the low-power nucleation of
skyrmions, which are required for the read and write operations. Here, we
demonstrate, using operando magnetic microscopy experiments, the electrical
detection of a single magnetic skyrmion in a magnetic tunnel junction (MTJ) and
its nucleation and annihilation by gate voltage via voltage control of magnetic
anisotropy. The nucleated skyrmion can be further manipulated by both gate
voltage and external magnetic field, leading to tunable intermediate resistance
states. Our results unambiguously demonstrate the readout and voltage
controlled write operations in a single MTJ device, which is a major milestone
for low power skyrmion based technologies.
