Evidence for magnetic field induced changes of the phase of tunneling states: spontaneous echoes in (KBr)(1-x)(KCN)(x) in magnetic fields.
Recently it was discovered that, in contrast to expectations, the low-temperature dielectric properties of some multicomponent glasses depend strongly on magnetic fields. The low-temperature dielectric response of these materials is governed by atomic tunneling systems. We now have investigated the influence of magnetic fields on the coherent properties of atomic tunneling states in a crystalline host in two-pulse echo experiments. As in glasses, we observe a very strong magnetic field dependence of the echo amplitude. Moreover, for the first time we have direct evidence that the magnetic fields change the phase of coherent tunneling systems.
Kirchhoff-Institut für Physik, Universität Heidelberg, Albert-Ueberle-Strasse 3-5, Germany.
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