Visualizing the intricate electron pairing in iron-based superconductors

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15 Νοε 2013 (πριν από 3 χρόνια και 10 μήνες)

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A Materials Research Science and Engineering Center Program Highlight

Visit the CCMR online at http://www.ccmr.cornell.edu

Research supported by NSF DMR
-
1120296

(Top)

Experimental

images

reveal

the

spatial

dependence

of

the

motion

of

electron

pairs

with

two

different

energies
.

The

(right)

red

and

(left)

gold

“bananas”

in

the

insets

indicate

favorable

directions

of

motion,

whereas

the

green

arrows

indicate

unfavorable

directions
.

(Bottom)

A

three
-
dimensional

representation

of

the

same

data,

showing

the

bonding

energies

two

pair

types

in

red

(lower

energy)

and

gold

(higher

energy)
.


Superconducting

wires

conduct

electricity

perfectly



without

any

energy

losses



because

each

electron

spontaneously

bonds

to

a

partner

electron
.

The

pairs

then

perform

an

intricate

dance

down

the

wire,

never

bumping

into

the

walls

or

other

pairs
.

Unfortunately,

the

pairs

are

usually

weak,

breaking

apart

at

all

but

the

coldest

temperatures,

destroying

the

superconductivity

and

limiting

most

practical

applications
.

Scientists

are

pursuing

the

possibility

of

electron

pairing

in

a

special

class

of

materials

(nearly

antiferromagnetic

compounds)

hoping

to

find

magnetically

mediated

superconductivity

at

ever

higher

temperatures
.

For

the

first

time,

researchers

at

Cornell

University

have

directly

imaged

the

intricate

dance

of

electron

pairs

in

a

new

type

of

iron
-
based

superconductor

using

a

highly

specialized

scanning

tunneling

microscope
.

As

predicted

by

theories

of

magnetically

mediated

electron

pairing,

the

strength

of

electron
-
electron

bonding

is

different

for

electrons

travelling

in

different

directions
.

The

electronic

structure

images

provide

new

clues

to

the

magnetic

origin

of

high
-
temperature

superconductivity,

bringing

practical

superconductors

a

step

closer

to

reality
.

Visualizing the intricate electron pairing in iron
-
based superconductors

Correlated motion provides new clues to the magnetic origin of high
-
temperature superconductivity



M
.

P
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Allan,

A
.

W
.

Rost,

A
.

P
.

Mackenzie,

Y
.

Xie,

J
.

C
.

Davis,

K
.

Kihou,

C
.

H
.

Lee,

A
.

Iyo,

H
.

Eisaki,

and

T
.
-
M
.

Chuang,

,

Science

336
,

563
-
567
,

(
2012
)
.