Order-by-disorder effects in antiferromagnets on face-centered cubic lattice

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:414

Article

Batalov, L. A.¹  Syromyatnikov, A. V.^1,2 

[1] BP Konstantinov Petersburg Nucl Phys Inst, Kurchatov Inst, Natl Res Ctr, Gatchina 188300, Russia

[2] St Petersburg State Univ, 7-9 Univ Skaya Nab, St Petersburg 199034, Russia

关键词: order by disorder phenomena;    Antiferromagnets;    Spin waves;    Frustration;    Quantized spin models;   

DOI  :  10.1016/j.jmmm.2016.04.052

来源: Elsevier

【 摘 要 】

We discuss the role of quantum fluctuations in Heisenberg antiferromagnets on face-centered cubic lattice with small dipolar interaction in which the next-nearest-neighbor exchange coupling dominates over the nearest-neighbor one. It is well known that a collinear magnetic structure which contains (111) ferromagnetic planes arranged antiferromagnetically along one of the space diagonals of the cube is stabilized in this model via order-by-disorder mechanism. On the mean-field level, the dipolar interaction forces spin to lie within (111) planes. By considering I/S corrections to the ground state energy, we demonstrate that quantum fluctuations lead to an anisotropy within (111) planes favoring three equivalent directions for the staggered magnetization (e.g., [11 (2) over bar], [1 (2) over bar1], and [(2) over bar 11] directions for (111) plane). Such in-plane anisotropy was obtained experimentally in related materials MnO, alpha-MnS, alpha-MnSe, EuTe, and EuSe. We find that the order-by-disorder mechanism can contribute significantly to the value of the in-plane anisotropy in EuTe. Magnon spectrum is also derived in the first order in I/S. (C) 2016 Elsevier B.V. All rights reserved.

【 授权许可】

Free