Harmonic maps from R2 or one-connected domain Ø ⊂ R2 into GL(m, C) and U(m) are treated. The GBDT version of the BäcklundDarboux transformation is applied to the case of the harmonic maps. A new general formula on the GBDT transformations of the Sym-Tafel immersions is derived. A class of the harmonic maps similar in certain ways to line-solitons is obtained explicitly and studied. MSC2000: 53C...

We extend many known results for harmonic maps from the 2-sphere into a Grassmannian to of finite uniton number an arbitrary Riemann surface. Our method relies on new theory nilpotent cycles arising diagrams F.E. Burstall and second author associated such maps; these properties arise criterion finiteness found recently by authors with A. Aleman. Applications include classification result minima...