论文标题
2D材料和薄磁性膜的高性能宽带法拉第旋转光谱
High-performance broadband Faraday rotation spectroscopy of 2D materials and thin magnetic films
论文作者
论文摘要
我们提出了一种用于微米尺度测量的法拉第旋转光谱（FRS）技术。证明了比最先进的调制光谱设置快的频谱采集速度。实验方法基于电荷耦合设备检测，避免了限制速度成分，例如具有锁定放大器的极化调节器。同时，在广泛的光谱范围内（525 nm-800 nm）的灵敏度为20 $μ$ rad（0.001 $^\ circ $），获得FRS光谱，与最新的极化调制技术相当。新的测量技术还自动取消不需要的法拉第旋转背景。使用该设置，我们在室温和液态氦气温度下，在磁场下，在高达1.4 t的HBN固定在原子上薄的半导体WS $ _2 $中，进行了激子的法拉第旋转光谱。我们在室温下确定-4.4 $ \ pm $ 0.3的激子G因子，在液态氦气温度下为-4.2 $ \ pm $ 0.2。此外，我们在20 nm厚的薄膜上执行FRS和磁滞回路测量，该薄膜的无定形磁性TB $ _ {0.2} $ fe $ _ {0.8} $ Alloy。
We present a Faraday rotation spectroscopy (FRS) technique for measurements on the micron scale. Spectral acquisition speeds of many orders of magnitude faster than state-of-the-art modulation spectroscopy setups are demonstrated. The experimental method is based on charge-coupled-device detection, avoiding speed-limiting components, such as polarization modulators with lock-in amplifiers. At the same time, FRS spectra are obtained with a sensitivity of 20 $μ$rad (0.001$^\circ$) over a broad spectral range (525 nm - 800 nm), which is on par with state-of-the-art polarization-modulation techniques. The new measurement technique also automatically cancels unwanted Faraday rotation backgrounds. Using the setup, we perform Faraday rotation spectroscopy of excitons in a hBN-encapsulated atomically thin semiconductor WS$_2$ under magnetic fields of up to 1.4 T at room temperature and liquid helium temperature. We determine the A exciton g-factor of -4.4 $\pm$ 0.3 at room temperature, and -4.2 $\pm$ 0.2 at liquid helium temperature. In addition, we perform FRS and hysteresis loop measurements on a 20 nm thick film of an amorphous magnetic Tb$_{0.2}$Fe$_{0.8}$ alloy.
