Collective impurity effects in the Heisenberg triangular antiferromagnet

International Conference on Strongly Correlated Electron Systems 2014

Maryasin, V.S.^1 ; Zhitomirsky, M.E.^2

University Grenoble-Alps, INAC-SPSMS, Grenoble

F-38000, France^1

Service de Physique Statistique, Magnétisme et Supraconductivité, INAC, CEA, 17 rue des Martyrs, Grenoble Cedex 9

38054, France^2

关键词: Biquadratic exchange;    Clustering mechanism;    Degeneracy lifting;    External magnetic field;    Heisenberg antiferromagnets;    Impurity concentration;    Non-magnetic impurities;    Triangular lattice;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/592/1/012112/pdf
DOI  :  10.1088/1742-6596/592/1/012112

来源: IOP

【 摘 要 】

We theoretically investigate the Heisenberg antiferromagnet on a triangular lattice doped with nonmagnetic impurities. Two nontrivial effects resulting from collective impurity behavior are predicted. The first one is related to presence of uncompensated magnetic moments localized near vacancies as revealed by the low-temperature Curie tail in the magnetic susceptibility. These moments exhibit an anomalous growth with the impurity concentration, which we attribute to the clustering mechanism. In an external magnetic field, impurities lead to an even more peculiar phenomenon lifting the classical ground-state degeneracy in favor of the conical state. We analytically demonstrate that vacancies spontaneously generate a positive biquadratic exchange, which is responsible for the above degeneracy lifting.