imaging the effects of individual impurity atoms in high-t c superconductors
DESCRIPTION
Electronic impurity-state at non-magnetic atom. Electronic impurity-state at magnetic atom. Zn On-site LDOS spectrum: W 0 =-1.5 meV. Magnetic Ni Atom. Non-magnetic Zn Atom. Bi 2 Sr 2 Ca(Cu 1-x Zn x ) 2 O 8+d : x 0. 3 % LDOS map at –1.5mV. - PowerPoint PPT PresentationTRANSCRIPT
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
Research Support:
Electronic impurity-state at non-magnetic atom
• Potential scattering should generate intra-gap state: Impurity-state is four-fold symmetric
• Oriented with gap nodes.
Balatsky, A.V., Salkola M.I., & Rosengren, A., Phys. Rev. B 51, 15547 (1995). Salkola, M.I., Balatsky, A.V., & Scalapino, D.J. Phys. Rev. Lett. 77, 1841 (1996).
UN8ln
1
UN2
1
FF0
99 .6 5 9093
2 .0 61 15410 9Fi j
j
9 9 .6 5 9 0 9 3
2 .0 6 1 1 5 41 09
F i j
j
-
O n-site p o te ntia l O n-site LDO S U> 0
LDOS Image at W ||2 for impurity-state
CuO2 Plane
Zn AtomClosed d-shellU>>0S=0
3.8 Å
Hole
•
Non-magnetic Zn Atom
Bi2Sr2Ca(Cu1-xZnx)2O8+d : x 0.3%Topo.
0 560 Å
0 5
60
Å
T = 4.2 K
200 pA, -200 mVNature 403, 746 (2000).
20,000 Bi atoms
~20 Zn atoms
Bi2Sr2Ca(Cu1-xZnx)2O8+d : x 0.3%LDOS map at –1.5mV
0 560 Å
0 5
60
Å
!10,000 Bi atoms
~20 Zn atoms
Junction Setpoint: 200 pA @ -200 mVNature 403, 746 (2000).
-200 -100 0 100 2000.0
0.5
1.0
1.5
2.0
2.5
Diffe
rentia
l Co
nd
uct
an
ce (
nS
)
Sample Bias (mV)
Zn On-site LDOS spectrum:0=-1.5 meV
Junction Setpoint: 200 pA @ -200 mVNature 403, 746 (2000).
CuO2 Plane
Ni Atomd8
U<0S=1
3.8 Å
•
Magnetic Ni Atom
3.75” sq. at1.55”, 2”
0 Å 60 Å
0 Å
6
0 Å
Topography (BiO Plane) Conductance Map, V = -1 mV
Junction Setpoint: 200 pA @ -200 mV
3.75” sq. at5.8”, 2”
0 Å 60 Å
0 Å
6
0 Å
Zn impurity-state location and orientation to dx2-
y2 gap nodes
b
a
Nature 403, 746 (2000).
• 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.
M.I. Salkola, A.V. Balatsky, J.R. Schrieffer, Phys. Rev. B 55, 12648 (1997).
M.E. Flatté and J.M. Byers, Sol. State. Phys. 52, 137 (1999).
•V(r)=Ud(r)+JS.s•|U|>|W| & U<0
On-site
WUN8ln(
1
WUN2
1
FF0
9 9 .6 5 9 0 9 3
2 .0 6 1 1 5 41 09
F i j
j
LDOS Image ||2 at both states
Ee V+
LDO S d I/d V
12 00
Electronic impurity-state at magnetic atom
91114I02
5.5” sq at
1.5”, 2.75”
0 Å 256 Å
256 Å
5000 Bi atoms
~30 Ni atoms
Bi2Sr2Ca(Cu1-xNix)2O8+d : x=0.5%Topo.
Nature 411 920 (2001).
T = 4.2 K
100 pA, -100 mV
91119c01 +10mV
+10 mV
Bi2Sr2Ca(Cu1-xNix)2O8+d : x=0.5%LDOS map at +10 mV
256 Å
0 Å 256 Å
Nature 411 920 (2001).
T = 4.2 K
100 pA, -100 mV
2500 Bi atoms
~30 Ni atoms
Ni On-site LDOS spectrum: W1~9 meV, W2~19 meV
Run 147: #2691126K00-19 Typical Spectrum (3a
above Ni Center)91127E00-20 Center Spectrum
-100 -50 0 50 1000.0
0.5
1.0
1.5
2.0
2.5
typical region on center of Ni atom
Diff
eren
tial C
ondu
ctan
ce (
nS)
Sample Bias (mV)
Nature 411 920 (2001).
Spin-up
Spin-down
+9 mV32 Å
0 Å
32 Å
91118a00 +9mV91117h14
b
a0 Å
Nature 411 920 (2001).
Ni impurity-state location and orientation to dx2-y
2 gap nodes