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One of the highlights in the study of geometrically frustrated magnets is the emergence of nontrivial excitations in spin liquid states, in particular through the interplay between different degrees of freedom, e.g. between spins and mobile electrons. Such interesting phenomena have been found in Pr$_2$Ir$_2$O$_7$, a metallic spin ice with two electronic sectors. One is Pr based spin ice, where strong quantum effects are expected for ferromagnetic exchange coupling and many similarities are found to the quantum spin ice candidate Pr$_2$Zr$_2$O$_7$. Another sector is the 5$d$ conduction electrons for which novel topological phases have been predicted based on the semimetallic half-filled $J_{¥rm eff} = 1/2$ band due to strong spin-orbit coupling. We will discuss our observations of chiral spin liquid and quantum criticality in Pr$_2$Ir$_2$O$_7$ and topological effects due to semimetallic electronic structure.

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Satoru Nakatsuji, ISSP Tokyo
Seminarraum Theorie (Neubau)
Contact: Simon Trebst