Imaging the Effects of Individual Impurity Atoms in High-T c Superconductors

1. Electronic impurity-state at non-magnetic atom Electronic impurity-state at magnetic atom Zn On-site LDOS spectrum: W0=-1.5 meV Magnetic Ni Atom Non-magnetic Zn Atom Bi2Sr2Ca(Cu1-xZnx)2O8+d: x  0.3% LDOS map at –1.5mV Ni On-site LDOS spectrum: W1~9 meV, W2~19 meV • M.I. Salkola, A.V. Balatsky, J.R. Schrieffer, Phys. Rev. B55, 12648 (1997). • M.E. Flatté and J.M. Byers, Sol. State. Phys.52, 137 (1999). • Balatsky, A.V., Salkola M.I., & Rosengren, A., Phys. Rev. B51, 15547 (1995). • Salkola, M.I., Balatsky, A.V., & Scalapino, D.J. Phys. Rev. Lett. 77, 1841 (1996). Ni impurity-state location and orientation to dx2-y2 gap nodes +9 mV LDOS Image at W |Y|2 for impurity-state Spin-up Zn Atom Closed d-shell U>>0 S=0 On-site LDOS Image |Y|2 at both states • V(r)=Ud(r)+JS.s • |U|>|W| & U<0 32 Å 32 Å Ni Atom d8 U<0 S=1 • • Spin-down Hole 10,000 Bi atoms ~20 Zn atoms CuO2 Plane CuO2 Plane 91118a00 +9mV ! Run 147: #26 91126K00-19 Typical Spectrum (3a above Ni Center) 91127E00-20 Center Spectrum 91117h14 0 560 Å 3.75” sq. at 1.55”, 2” 3.75” sq. at 5.8”, 2” 0 Å 60 Å 0 Å 60 Å b a 0 Å 0 Å 3.8 Å 3.8 Å 0 Å 60 Å 0 Å 60 Å • Potential scattering generates intra-gap impurity-state • Magnetic interactions lift the spin-degeneracy • Two spin-polarized states created at W1 and W2 • On-site component of both impurity-states is four-fold symmetric, • pointing at gap nodes. • Potential scattering should generate intra-gap state: Impurity-state is four-fold symmetric • Oriented with gap nodes. Topography (BiO Plane) Conductance Map, V = -1 mV 0 560 Å Junction Setpoint: 200 pA @ -200 mV Junction Setpoint: 200 pA @ -200 mV Nature 403, 746 (2000). Nature 403, 746 (2000). Nature 411 920 (2001). Nature 411 920 (2001). Imaging the Effects of Individual Impurity Atoms in High-Tc Superconductors E.W. Hudson, K. M. Lang, J. E. Hoffman, S. H. Pan, H. Eisaki, S. Uchida & J. C. Seamus Davis Bi2Sr2Ca(Cu1-xZnx)2O8+d: x0.3% Topo. 20,000 Bi atoms ~20 Zn atoms 0 560 Å 0 560 Å T = 4.2 K 200 pA, -200 mV Nature 403, 746 (2000). Zn impurity-state location and orientation to dx2-y2 gap nodes b a Junction Setpoint: 200 pA @ -200 mV Nature 403, 746 (2000). Bi2Sr2Ca(Cu1-xNix)2O8+d: x=0.5% Topo. 256 Å 5000 Bi atoms ~30 Ni atoms 5.5” sq at 1.5”, 2.75” 91114I02 0 Å 256 Å T = 4.2 K 100 pA, -100 mV Nature 411 920 (2001). Bi2Sr2Ca(Cu1-xNix)2O8+d: x=0.5% LDOS map at +10 mV 256 Å 2500 Bi atoms ~30 Ni atoms 91119c01 +10mV +10 mV 0 Å 256 Å T = 4.2 K 100 pA, -100 mV Nature 411 920 (2001). Research Support: