| 摘要 | In this proceeding, recent theoretical investigations by the authors on the multiferroic RMnO(3) perovskites are briefly reviewed at first. Using the double-exchange model, the realistic spiral spin order in undoped manganites such as TbMnO(3) and DyMnO(3) is well reproduced by incorporating a weak next-nearest neighbor superexchange (similar to 10% of nearest neighbor superexchange) and moderate Jahn-Teller distortion. The phase transitions from the A-type antiferromagnet (as in LaMnO(3)), to the spiral phase (as in TbMnO(3)), and finally to the E-type antiferromagnet (as in HoMnO(3)), with decreasing size of the R ions, were also explained. Moreover, new results of phase diagram of the three-dimensional lattice are also included. The ferromagnetic tendency recently discovered in the LaMnO(3) and TbMnO(3) thin films is explained by considering the substrate stress. Finally, the relationship between our double-exchange model and a previously used J(1)-J(2)-J(3) model is further discussed from the perspective of spin wave excitations. |
| 部门归属 | [dong, s.; yu, r.; dagotto, e.] univ tennessee, dept phys & astron, knoxville, tn 37996 usa. [dong, s.; yu, r.; dagotto, e.] mat sci & technol div, oak ridge natl lab, oak ridge, tn 38231 usa. [dong, s.; liu, j. -m.] nanjing univ, nanjing natl lab microstruct, nanjing 210093, peoples r china. [yunoki, s.] riken, computat condensed matter phys lab, wako, saitama 3510198, japan. [yunoki, s.] japan sci & technol agcy, crest, kawaguchi, saitama 3320012, japan. [liu, j. -m.] chinese acad sci, int ctr mat phys, shenyang 110016, peoples r china.;dong, s (reprint author), univ tennessee, dept phys & astron, knoxville, tn 37996 usa;saintdosnju@gmail.com
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