The solar sail material described here has a maximum operating temperature of 2773 deg. Kelvin. I can only speculate as to the reflectivity and emissivity, but let's be optimistic and say they are both 0.98. That means the sail could withstand up to 164,277,701 watts per square meter of radiation, which is probably impossible. But anyway, with an area density of only 0.005 kg per square meter, full on radiation pressure would accelerate it at 0.547971427 meters per second squared.

Imagine the solar sail moving around a circular track, with the Sun at the center. A beam could be transmitted from close to the Sun, to a ring of reflectors positioned around the track. As the sail travelled around the imaginary track, the beam would be reflected back inward, striking the sail and giving it a push inward, toward the sun. The sail could thus be confined to a circular path around the Sun.

Unfortunately, for a tangential velocity of 0.1 lightspeed, the track radius would have to be 54.82 AU, or 38.5 percent further from the Sun than Pluto. While Pluto orbits once every 249 years, the solar sail would whip around the Sun once every 47.745 hours. There are already two spacecraft that are alot further from the Sun: Voyager I has passed 88 AU, and Voyager II is more than 70 AU from the Sun. The solar sail, launched at this velocity would reach Alpha Centauri in 43 years. There is slim hope of reducing the travel time since the radius of the track would increase with the square of the tangential velocity. Also don't ask me how many reflector platforms would be needed, or how it would decelerate upon arrival at it's destination. The plus side is that it would use raw solar energy, no laser power conversion losses. Solar is also a bottomless pit power source, guaranteed to last 5 billion years (better than Energizer).

A solar sail made of the same material, accelerating in a straight line rather than a circle, would need an imaginary runway 5482 AU long, which is more than 2 percent of the distance to Alpha Centauri. The amount of beamed energy infrastructure for this application is well beyond most people's tolerance for speculation I think.