Magnetospectroscopy of acceptors in "blue" diamonds

Abstract

Naturally occurring, nitrogen-free, p- type diamond— now known to be boron-doped— as well as man-made diamonds deliberately doped with boron display an electronic Raman transition, Δ', originating in the 1s(p_3/2) : Γ ₈ ground state of the acceptor and terminating in its 1s(p_½ ) : Γ ₇ spin-orbit partner. With magnetic field B along [0 0 1], [1 1 1], or [1 1 0], the electronic Raman spectrum displays eight Zeeman transitions and four Raman lines ascribed to transitions between the Zeeman sublevels of Δ ₈ (Raman-electron-paramagnetic-resonance: Raman-EPR). They exhibit polarizations expected from the polarizability tensors formulated in terms of the Luttinger parameters γ₁, γ ₂, and γ₃ characterizing the top of the valence band. The selection rules and the relative intensities of the Zeeman components as well as of the Raman-EPR lines, observed in diverse polarization configurations and scattering geometries, have led to: assignments of magnetic quantum numbers; the level ordering of the Zeeman sublevels, or equivalently, the magnitudes and signs of g₁ and g₂, the orbital and spin g-factors of the acceptor-bound hole; the extreme mass anisotropy as reflected in the ratio (γ₂/γ ₃)=0.08± 0.01. Magnetic-field-nduced mixing of zero field states, time reversal symmetry, and the diamagnetic contributions which characterize the different sublevels are fully taken into account in the interpretation of the experimental results. These include the striking mutual exclusion of the Stokes spectrum from its anti-Stokes counterpart in specific polarization configurations.