Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 4: Electron Theory of Magnetism

MA 4.7: Vortrag

Montag, 26. März 2007, 11:45–12:00, H23

Magnetic properties of Cr teluride-selenide alloys — •Sergey Mankovsky¹, Svetlana Polesya¹, Hubert Ebert¹, Zhong-Le Huang², and Wolfgang Bensch² — ¹Dept. Chemie und Biochemie, Universität München, Butenandtstr. 5-13,
D-81377 München, Germany — ²Institute for Anorganic Chemistry, Olshausenstr. 40, D-24098, Kiel, Germany

Results of a theoretical study of the magnetic properties of Cr telluride-selenide alloys having trigonal crystal structure are presented in comparison with experimental results. Both ground state and temperature-dependent magnetic properties of Cr_1−δTe and Cr_x(Te_αSe_β)₂ (with ratio α : β = 7:1, 6:2, 5:3) have been investigated in a wide region of chromium content. For the alloys Cr_x(Te_αSe_β)₂ a transition to the state with antiferromagnetic order in a fully occupied sub-lattice and with no order in a partially occupied sub-lattice was obtained. For the alloys Li_xCr_0.5Ti_0.75Se₂, a non-monotonic dependence of structural and magnetic properties have been found upon increase of Li concentration x, that is in agreement with experimental results.

The ground state properties have been studied on the basis of electronic structure calculations using the Korringa-Kohn-Rostoker (KKR) band structure method combined with the CPA alloy theory. Using Monte Carlo simulations we obtained the magnetic configuration at T = 0K and studied the magnetic properties at T > 0K as well. The required exchange coupling parameters were obtained from our ab-initio electronic structure calculations.