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

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