Theoretical Calculations of Strain—Induced Splittings and/or Shifts of t2^32E and t2^34A2 Levels for MgO:Cr^3+ |
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摘 要: |
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关 键 词: | 晶体 MgO:Cr^3+ 能级位移 混合波函数 |
收稿时间: | 2000-09-25 |
Theoretical Calculations of Strain-Induced Splittings and/or Shifts of t232E and
t234A2
Levels for MgO:Cr3+ |
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Authors: | MA Dong-Ping MA Ning and CHEN Ju-Rong |
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Institution: | 1. Department of Applied Physics, Sichuan University, Chengdu 610065, China
;2. International Centre for Materials Physics, The Chinese Academy of Sciences, Shenyang 110015, China
;3. Department of Computer Science, Sichuan University, Chengdu
610064, China |
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Abstract: | Under various uniaxial stresses, both strains with low symmetry and isotropic strains of crystals take place. The former gives the strain-induced low-symmetry crystal fields and accordingly
splittings of levels; the latter gives the isotropic parts of strain-induced crystal fields and accordingly shifts of levels. By using the wavefunctions obtained from the diagonalization
of the complete d^3$ energy matrix in a regular octahedral field,
the relevant matrix elements and accordingly strain-induced splittings
and/or shifts of t232E and t234A2 for MgO:Cr3+ have been calculated. Their physical
origins have been thoroughly analyzed and revealed. It is the admixtures of basic wavefunctions resulted from the spin-orbit interaction and/or Coulomb interaction and/or Kramers degeneracy
that make strain-induced splittings of levels nonzero. In contrast with this, strain-induced shifts come mainly from the zero-order approximate wavefunctions. It is found that there are nonvanishing matrix elements of operators T2ξ, T2η and T2ζ
between wavefunctions with positive Ms and those with
negative Ms', which have important effects on strain-induced splittings of levels. The shifts of
t232E
under both hydrostatic pressure and uniaxial pressure have been uniformly calculated. The important results of Yc, Zc, Pc, Qc and
〈t2|| C(A1)||
t2〉have been evaluated. |
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Keywords: | strain and stress splitting and shift of levels ligand field admixture of wavefunctions single-electron reduced matrix elements |
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