Further study of the Mn<sup>2+</sup> EPR centre in ferro- and para-elastic BiVO<sub>4</sub>:spin Hamiltonian parameters and temperature dependence
T H Yeom; S H Choh; M S Jang; T H Yeom; Dept. of Phys., Korea Univ., Seoul, South Korea; S H Choh; Dept. of Phys., Korea Univ., Seoul, South Korea; M S Jang; Dept. of Phys., Korea Univ., Seoul, South Korea
Журнал:
Journal of Physics: Condensed Matter
Дата:
1992-01-13
Аннотация:
The electron paramagnetic resonance (EPR) of an Mn<sup>2+</sup> (S=5/2) impurity in the ferroelastic and para-elastic phase of BiVO<sub>4</sub> crystals with a single domain, grown by the Czochralski method, has been investigated using an X-band spectrometer. The rotation patterns of the resonance fields measured on the crystallographic planes are analysed: g=1.9940+or-0.0009, D/h=2.443+or-0.002, E/h=0.4912+or-0.0009, F/h=0.094+or-0.002, B<sub>4</sub><sup>2</sup>/h=0.0, A<sub>x</sub>/h=0.27+or-0.02, A<sub>y</sub>/h=0.25+or-0.02, and A<sub>z</sub>/h=0.33+or-0.02 GHz at room temperature (<T<sub>c</sub>=528 K); and g=1.994+or-0.001, D/h=0.000+or-0.004, E/h=0.000+or-0.004, F/h=0.00+or-0.01, A/h=0.25+or-0.01 GHz at T=535 K (>T<sub>c</sub>). The principal x, y, and z axes of the D-tensor are found to be along the crystallographic b, c+45 degrees and a+45 degrees axes, respectively. This Mn<sup>2+</sup> centre has the correct principal axes system of the D-tensor compared with the previous Mn<sub>I</sub> centre. The D-value decreases as the temperature increases in the range 107-535 K. It is proposed that the Mn<sup>2+</sup> ion substitutes for Bi<sup>3+</sup> without nearby charge compensation.
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