Fig. 2
From: Microsecond dark-exciton valley polarization memory in two-dimensional heterostructures
Valley polarization with CW laser excitation. a, b Valley polarization at 0 T. Right and left circularly polarized light are labeled as σ+ and σ−. Under σ+ laser excitation, σ+ PL output component is more than σ− and vice versa for σ− excitation. This shows evidence of valley polarization. c, d Valley polarization at −7 T. Valley polarization is enhanced by applying magnetic field perpendicular to the sample surface. e The valley polarization degree as a function of applied magnetic field in the z direction. The solid line is the fitting result following equation \(P^j = P_0^j \pm P_1^j\left( {1 - \frac{1}{{r^2 + r\sqrt {1 + r^2} + 1}}} \right)\), \(r = \left| B \right|{\mathrm{/}}\alpha\) where j indicates the excitation polarization, \(P_0^j\) is the residual degree of polarization at 0 T due to the valley polarization, \(P_1^j\) is the saturation level of degree of polarization, and α represents the intervalley scattering between the dark exciton. f, The valley polarization degree as a function of applied magnetic field in the y direction with B z = 0T
