TRR 360 Seminar:

Randomness, disorder and compromises in magnetic systems

Ellen Fogh

Randomness, disorder and compromises in magnetic systems

Prof. Dr. Ellen Fogh

Technical University of Munich

The interplay between randomness, disorder and frustration in magnetic systems may bring about interesting ground states and behaviours. Many real materials display intrinsic inhomogeneity, as a result of impurities or (counter)ion substitution, that results in site or bond disorder. This is known as quenched randomness, and the loss of translational symmetry it entails makes the system challenging to study theoretically. However, quenched randomness in magnetic systems can lead to specific ground states with no long-ranged order, including glassy states and the random-singlet state but also various long-range ordered states. Some of these phases of matter are closely related to certain types of quantum spin liquids and thus raise the question of whether randomness in a frustrated system can produce qualitatively different types of quantum coherence, as opposed to only destroying such coherence. Here, I discuss three specific cases of how randomness and disorder have profound consequences for physical behaviour of such magnetic systems.