Figure 8
From: Sub-lattice of Jahn-Teller centers in hexaferrite crystal
Temperature dependences of dielectric characteristics (a) and elastic modulus \({c}_{44}\) (b) of single-crystalline BaFe11.25Ti0.75O19. Dielectric permittivity ε′ was measured at the frequency of 0.3 THz (wavenumber 10 cm−1) for two principle polarizations of the electric field vector of the probing radiation relative to the c-axis, E⊥c (blue color) and E | | c (black color), as indicated. The red dots show the dielectric contribution Δε of the terahertz absorption resonance in BaFe10.85Ti1.15O19. Lines are guides to the eye. The modulus \({c}_{44}\) is presented for three conditions: dynamic (line 1), relaxed (2), and unrelaxed (3). Line 4 corresponds to \(\Delta {c}_{44}/{c}_{0}=-\,0.009-0.000143\cdot T\), line 5 - to \(\Delta {c}_{44}/{c}_{0}=0.002-0.000287\cdot T\). Here \(\Delta {c}_{44}={c}_{44}(T)-{c}_{0}\), \({c}_{0}={c}_{44}({T}_{0})\) and \({T}_{0}=2\,{\rm{K}}\).
