中国物理B ›› 2013, Vol. 22 ›› Issue (6): 66201-066201.doi: 10.1088/1674-1056/22/6/066201

• CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES • 上一篇    下一篇

A first-principles study of the structural and elastic properties of orthorhombic and tetragonal Ca3Mn2O7

张玮a, 童培庆a b   

  1. a Department of Physics, Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023, China;
    b Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems, Nanjing Normal University, Nanjing 210023, China
  • 收稿日期:2012-12-04 修回日期:2013-03-05 出版日期:2013-05-01 发布日期:2013-05-01
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 11175087) and the Project of Graduate Students' Education and Innovation Foundation of Jiangsu Province (Grant No. CXZZ12_0388).

A first-principles study of the structural and elastic properties of orthorhombic and tetragonal Ca3Mn2O7

Zhang Wei (张玮)a, Tong Pei-Qing (童培庆)a b   

  1. a Department of Physics, Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023, China;
    b Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems, Nanjing Normal University, Nanjing 210023, China
  • Received:2012-12-04 Revised:2013-03-05 Online:2013-05-01 Published:2013-05-01
  • Contact: Tong Pei-Qing E-mail:pqtong@njnu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 11175087) and the Project of Graduate Students' Education and Innovation Foundation of Jiangsu Province (Grant No. CXZZ12_0388).

摘要: The structural and elastic properties of multiferroic Ca3Mn2O7 with ferroelectric orthorhombic (O-phase) and paraelectric tetragonal structures (T-phase) have been studied by first-principles calculations within the generalized gradient approximation (GGA) and the GGA plus Hubbard U approaches (GGA+U). The calculated theoretical structures are in good agreement with the experimental values. The T-phase is found to be antiferromagnetic (AFM) and the AFM O-phase is more stable than the T-phase, which also agree with the experiments. On these basis, the single-crystal elastic constants (Cijs) and elastic properties of polycrystalline aggregates are investigated for the two phases. Our elasticity calculations indicate Ca3Mn2O7 is mechanically stable against volume expansions. The AFM O-phase is found to be a ductile material, while the AFM T-phase shows brittle nature and tends to be elastically isotropic. We also investigate the influence of strong correlation effects on the elastic properties, qualitatively consistent results are obtained in a reasonable range of values of U. Finally, the ionicity is discussed by Bader analysis. Our work provides useful guidance for the experimental elasticity measurements of Ca3Mn2O7, and makes the strain energy calculation in multiferroic Ca3Mn2O7 thin films possible.

关键词: elastic constant, elastic anisotropy, strong correlation effect, multiferroic

Abstract: The structural and elastic properties of multiferroic Ca3Mn2O7 with ferroelectric orthorhombic (O-phase) and paraelectric tetragonal structures (T-phase) have been studied by first-principles calculations within the generalized gradient approximation (GGA) and the GGA plus Hubbard U approaches (GGA+U). The calculated theoretical structures are in good agreement with the experimental values. The T-phase is found to be antiferromagnetic (AFM) and the AFM O-phase is more stable than the T-phase, which also agree with the experiments. On these basis, the single-crystal elastic constants (Cijs) and elastic properties of polycrystalline aggregates are investigated for the two phases. Our elasticity calculations indicate Ca3Mn2O7 is mechanically stable against volume expansions. The AFM O-phase is found to be a ductile material, while the AFM T-phase shows brittle nature and tends to be elastically isotropic. We also investigate the influence of strong correlation effects on the elastic properties, qualitatively consistent results are obtained in a reasonable range of values of U. Finally, the ionicity is discussed by Bader analysis. Our work provides useful guidance for the experimental elasticity measurements of Ca3Mn2O7, and makes the strain energy calculation in multiferroic Ca3Mn2O7 thin films possible.

Key words: elastic constant, elastic anisotropy, strong correlation effect, multiferroic

中图分类号:  (Elastic moduli)

  • 62.20.de
64.30.Jk (Equations of state of nonmetals) 71.15.Mb (Density functional theory, local density approximation, gradient and other corrections) 71.27.+a (Strongly correlated electron systems; heavy fermions)