Khaliullin G, Horsch P, Oleś A M
Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
Phys Rev Lett. 2001 Apr 23;86(17):3879-82. doi: 10.1103/PhysRevLett.86.3879.
We investigate the highly frustrated spin and orbital superexchange interactions in cubic vanadates. The fluctuations of t(2g) orbitals trigger a novel mechanism of ferromagnetic interactions between spins S = 1 of V3+ ions along one of the cubic directions which operates already in the absence of Hund's rule exchange J(H), and leads to the C-type antiferromagnetic phase in LaVO3. The Jahn-Teller effect can stabilize the orbital ordering and the G-type antiferromagnetic phase at low temperatures, but large entropy due to orbital fluctuations favors again the C phase at higher temperatures, as observed in YVO (3).
我们研究了立方钒酸盐中高度受挫的自旋和轨道超交换相互作用。t(2g)轨道的涨落引发了一种新型机制，即沿立方方向之一的V3+离子的自旋S = 1之间的铁磁相互作用，这种相互作用在没有洪德规则交换J(H)的情况下就已起作用，并导致LaVO3中出现C型反铁磁相。 Jahn-Teller效应可以在低温下稳定轨道有序和G型反铁磁相，但如在YVO(3)中所观察到的，由于轨道涨落导致的大熵在较高温度下又有利于C相。
