Multiple-well tunneling model for the magnetic-field effect in ultracold glasses

Puzzling observations of unusual responses of some multisilicate glasses at temperatures T <1 K to static magnetic fields B have been reported in the last decade and call for an extension of the standard two-level systems tunneling model. An explanation is proposed capable of capturing at the same time the T and B dependences of the heat capacity Cp and of the dielectric constant isin in these glasses. This theory points to the existence of anomalous multiwelled tunneling systems in the glasses - alongside the standard two-level systems - and indications are given for glasses which should achieve much larger electric magnetocapacitive enhancements.