Dr. Andrej Zorko: Frustration-Driven Phase Separation in a Spin System

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Frustration-Driven Phase Separation in a Spin System

Dr. Andrej Zorko, Jozef Stefan Institute, Ljubljana

Geometrical frustration, an inability to simultaneously minimize all local interactions because of geometric constraints, is a fruitful mechanism, responsible for a variety of intriguing phenomena. These range from exotic spin-liquid and spin-ice states, multiferroicity and possibly even superconductivity in condensed matter, to nanotube shape formation and protein folding. Due to an extensive number on different ground-state configurations commonly encountered in geometrically frustrated spin systems, the frustration was theoretically suggested to cause phase separation on a nanoscale. Electronic phase separation that breaks translational symmetry of chemically homogeneous systems is a fascinating effect, well known from high-Tc cuprates, colossal magnetoresistive manganites and many other transition-metal oxides. It is related to competing degrees of freedom and it generally requires active charge degrees of freedom. I will present a completely different example of an intrinsically inhomogeneous state that was recently experimentally detected on a triangular spin lattice. The crucial role of geometrical frustration and near-degenerate crystal structures in stabilizing this paradigmatic state of matter will be discussed.