Quantum dots with even number of electrons: Kondo effect in a finite magnetic field

We show that the Kondo effect can be induced by an external magnetic field in quantum dots with an even number of electrons. If the Zeeman energy B is close to the single-particle level spacing Delta in the dot, the scatterin g of the conduction electrons from the dot is dominated by an anisotropic e xchange interaction. A Kondo resonance then occurs despite the fact that B exceeds by far the Kondo temperature T-K. As a result, at low temperatures T much less than T-K the differential conductance approaches a unitary limi t G(K) similar to e(2)/pi h. A possible experimental realization or this ef fect is discussed.