Münster 1999 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 7: Heavy Fermions

TT 7.2: Vortrag

Dienstag, 23. März 1999, 10:00–10:15, F1

Heavy fermion formation and magnetic interactions in LiV₂O₄ — •V. Eyert^1,2, K.-H. H"ock², S. Horn², A. Loidl², and P. S. Riseborough³ — ¹Hahn-Meitner-Institut, D-14109 Berlin — ²Institut f"ur Physik, Universit"at Augsburg, D-86135 Augsburg — ³Physics Dept., Polytechnic University, New York, N.Y. 11201

We present results of all-electron electronic structure calculations for the recently discovered d electron heavy fermion compound LiV₂O₄ . The augmented spherical wave calculations are based on density functional theory within the local density approximation. The electronic properties are dominated by O 2p and crystal field split V 3d orbitals. Electronic bands near the Fermi energy originate almost exclusively from V 3d t_2g states. Allowing for spin polarization we arrive at a, however geometrically frustrated, antiferromagnetic ground state and an additional ferromagnetic solution. On varying the V – O bondangle we find drastic changes almost exclusively of the narrow local V 3d_3z²−r2 ( a_1g ) states pointing along the ⟨111⟩ direction, which split off from the t_2g states due to the small trigonal component of the crystal field, while the remaining, rather broad e_g^π states are essentially unaffected. In the spin-polarized calculations, this leads to a change of the local magnetic moments as well as a crossover from antiferro- to ferromagnetic order.