F A C I L I T I E S
ERPES (Extreme Resolution ARPES) (가칭)
ERPES is our state-of-the-art ARPES system under development.
Equipped with a Scienta Omicron DA30-L-8000 hemispherical electron analyzer, ERPES will ultimately be able to achieve sub-meV energy resolution combined with a spatial resolution in the order of 10 μm, while maintaining extreme sample temperatures below 1.5 K within a compact footprint. Our custom-designed 6-axis sample manipulator consists of piezoelectric actuators from moeemotion that include resistive encoders with < 1 μm linear or < 0.02° angular resolution. With the microfocused beam and the low-vibration pulse tube refrigerator, we will be able to routinely obtain excellent spatial resolution. To maximize acquisition efficiency and eliminate the vacuum space charge effect, we use a continuous wave 6 eV laser from LEOS Solutions as the light source. We have currently achieved a sample temperature of 1.6 K and a beam spot size of < 50 μm, and are conducting further optimization.
Synchrotron ARPES
A bright light source with high and tunable photon energy is required to access a broad range of momentum space with ARPES. Synchrotron radiation is the only option that meets these requirements. We are heavy users of synchrotron facilities around the globe, in particular, the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory and the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC National Accelerator Laboratory. With the advent of elliptically polarizing undulators, the polarization of incident photons are easily tunable, allowing for convenient polarization-dependent experiments.
Sample growth & characterization
Large and homogeneous single crystal samples are essential for ARPES. We grow high quality bulk single crystals for our ARPES experiments with various methods including chemical vapor transport and the flux method. We are equipped with 5 two zone furnaces, a box furnace, and a quartz ampoule sealing apparatus along with a glove box for air sensitive samples. The synthesized samples are characterized using various methods including transport measurements, X-ray diffraction, and energy dispersive X-ray spectroscopy.