Wavefunction Imaging Scanning Tunneling Microscopy

1. ULV-STS Lab Performance Tip-Sample Tunneling Current 20 2500 Å 15 Differential Conductance (nS) 10 3.75” sq. at 5.8”, 2” 5 Apply a voltage V lowers EF of sample by eV with respect to EF of tip 0 Å 0 Å 2500 Å 0 -8 -6 -4 -2 0 2 4 6 8 Sample Bias (mV) Wavefunction Imaging Scanning Tunneling Microscopy K. McElroy, J. Lee, J. E. Hoffman, E.W. Hudson, K. M. Lang, & J. C. Seamus Davis Bi2Sr2CaCu2O8+d Local Density of Electronic States 0 256 Å 5.5” sq at 1.5”, 2.75” 91114I02 256 Å 0 256 Å 91119c01 +10mV At 10s per spectrum, a 5122 pixel array requires 2.5X106 s ~ (1 month) 0 256 Å STS Instrument Design Ultra Low Vibration lab Design Rev. Sci. Inst. 70, 1459 (1999). Load Lock • Massive Lead+Concrete Cryostat • STM + High Field Magnet • Sample Exchange from RT • Cryogenic UHV Cleavage Turbo Pump to Pumps Lead Filled Table Air Springs L4He Fridge Cleaver Lead Legs STM Head Acoustic ‘Bunker’ High-field SC Magnet Cuprate High-Tc Studies Semiconductor Studies CDW Studies Ga(Te)As • Atomic –resolution mK-STM • Local state tunneling spectroscopy • Spectroscopic mapping of |Y|2 NbSe2 Nanoscale e-disorder Vortex Core-States Q. Interference Impurity-States For a dopant atom in GaAs (at T<20mK) we have demonstrated ……. 128 Å 56 nm 0-12mV LDOS,B=5T 64 nm 12 mV LDOS, B=0 26 nm -9mV LDOS, B=0 15 nm Gapmap, B=0 Nature 414 282 (2002) Science 296455 (2002) Science 297, 1148 (2002) Nature 411, 920 (2001) • Atomic –resolution mK-STM • Vortex core tunneling spectroscopy • Spectroscopic mapping of |Y|2 at Fe impurity atoms Research Support: