Figure 4: Experimental proof for fast DNP.
From: Efficient room-temperature nuclear spin hyperpolarization of a defect atom in a semiconductor
(a) Left panel: A two-dimensional plot of the total photoluminescence intensity of the band-to-band optical transition under alternating σ+ and σ− excitation as a function of time and Bz, obtained at RT from GaN0.026As0.974. The contrast from blue to red colour corresponds to weak to strong photoluminescence intensity. The white line is a guide to the eye, signifying the Overhauser shift. Right panel: The helicity of the excitation light as a function of time. (b) The horizontal cross-sectional plots of a at 41 (the blue open circles) and 91 μs (the red open circles), which correspond to the photoluminescence intensity obtained under pure σ+ and σ− excitation, respectively. The solid lines are Lorentzian fits of the experimental curves. (c) Differential photoluminescence intensity between σ+ and σ− excitation modulated at 10 (the black curve) and 100 kHz (the red curve), obtained by the locking-in technique in phase with σ+ excitation. a.u., arbitrary unit.
