Regensburg 2016 – scientific programme

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MA: Fachverband Magnetismus

MA 51: Magnetic Semiconductors

MA 51.6: Talk

Friday, March 11, 2016, 11:15–11:30, H13

Modeling Magnetism of Diluted Magnetic Systems using the Gutzwiller Method — •Thorben Linneweber¹, Ute Löw¹, Florian Gebhard², and Jörg Bünemann² — ¹Technische Universität Dortmund, Lehrstuhl für Theoretische Physik II, 44221 Dortmund — ²Philipps-Universität Marburg, AG Vielteilchenphysik, 35032 Marburg

Diluted magnetic semiconductors are materials in which magnetic ions substitutionally or interstitially replace a fraction of the cations of the semiconductor host material. We aim to describe the magnetic properties of the prototype substance Cd_1−xMn_xTe. We derive a multiband Hubbard model from DFT calculations using the Wannier90 code. Large unit cells (≈ 200 atoms) account for the randomized substitution of cations by magnetic ions. We analyze the ground state of this model within the framework of the Gutzwiller variational method. We find that the d-shell of the Mn ions resembles an atomic Hund’s rule S=5/2 ground state. Due to the superexchange mechanism, there is an effective short-range Heisenberg exchange between the magnetic ions. We estimate the exchange parameters using energy calculations of different magnetic configurations and finally compare them to experimental results.