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### Event Number 3322

**Condensed Matter Theory Group Seminar****Evolution of the magnetic ordering in iron-chalcogenide Fe(1+y)Te as a function of the level of interstitial Fe excess, y Time****Time:**4:30 pm**Place:**Chamberlin 5310**Speaker:**Samuel Ducatman, University of Wisconsin**Abstract:**We studied the electronic and magnetic properties of iron-chalcogenide Fe$_{1+y}$Te compounds based on the multiband model, in which localized spins and itinerant electrons coexist and are coupled by Hund's rule coupling. Integrating out the conduction electrons, we computed additional couplings between localized spins similarly to the conventional Ruderman-Kittel-Kasuya-Yosida (RKKY)theory. We found that resulting RKKY-like interactions are substantial up to the third neighbors, but are negligible beyond this. We computed the magnetic phase diagram of the modified $J_1-J_2-J_3-K$ model and showed it captures the evolution of the magnetic order in Fe$_{1+y}$Te as a function of Fe excess $y$.**Host:**Perkins- Add this event to your calendar