Electric Field Effect on the ESR Spectrum of Fe³⁺ in SrTiO₃

Abstract

The electric field effect of the electron spin resonance for Fe³⁺ in SrTiO₃ has been studied. The temperature and electric field dependence of the ESR shift indicates that the induced spin Hamiltonian should involve the square of induced polarization with the form (Remark: Graphics omitted.). When an electric field is applied along the ⟨100⟩ direction, the resultant variation of ESR spectrum is expressed by an induced axial term Δb₂⁰=(3⁄2)T₁₁P² with T₁₁=−2T₁₂=1.0×10⁻⁴cm⁻¹⁄(μC⁄cm²)². The 110 K structural phase transition in this crystal does not seem to affect the characteristics of the ESR Stark effect. The magnitude of the induced spin Hamiltonian parameter is discussed in several respects.